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259 results on '"European Theoretical Spectroscopy Facility (ETSF)"'

2. Identification of Low Hole Effective Mass Novel p-type Transparent Conducting Oxides by High-Throughput Computing

Author

UCL - SST/IMCN/NAPS - Nanoscopic Physics, Hautier, Geoffroy, Miglio, Anna, Ceder, G., Rignanese, Gian-Marco, Gonze, Xavier, European Theoretical Spectroscopy Facility (ETSF) workshop, UCL - SST/IMCN/NAPS - Nanoscopic Physics, Hautier, Geoffroy, Miglio, Anna, Ceder, G., Rignanese, Gian-Marco, Gonze, Xavier, and European Theoretical Spectroscopy Facility (ETSF) workshop

Published
2013

3. High-throughput ab initio computations for materials discovery and the Materials project Database

Author

UCL - SST/IMCN/NAPS - Nanoscopic Physics, Hautier, Geoffroy, Miglio, Anna, Rignanese, Gian-Marco, Gonze, Xavier, Jain, A., Persson, K., Ong, S.P., Ceder, G., European Theoretical Spectroscopy Facility (ETSF) workshop, UCL - SST/IMCN/NAPS - Nanoscopic Physics, Hautier, Geoffroy, Miglio, Anna, Rignanese, Gian-Marco, Gonze, Xavier, Jain, A., Persson, K., Ong, S.P., Ceder, G., and European Theoretical Spectroscopy Facility (ETSF) workshop

Published
2012

4. Pressure-induced radial collapse in few-wall carbon nanotubes: A combined theoretical and experimental study

Author

Tiago F. T. Cerqueira, Alfonso San-Miguel, Abraao C. Torres-Dias, Wenwen Cui, Christophe Laurent, David J. Dunstan, Denis Machon, Miguel A. L. Marques, Silvana Botti, Rafael S. Alencar, Alicia Weibel, Odair Pastor Ferreira, A. G. Souza Filho, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Martin-Luther-Universität Halle-Wittenberg - MLU (GERMANY), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Queen Mary University of London - QMUL (UNITED KINGDOM), Universidade Federal do Ceará (BRAZIL), Friedrich-Schiller-Universität Jena (GERMANY), European Theoretical Spectroscopy Facility - ETSF (Halle, Germany), Centre Interuniversitaire de Recherche et d'Ingénierie des Matériaux - CIRIMAT (Toulouse, France), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Universidade Federal do Ceará = Federal University of Ceará (UFC), Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], European Theoretical Spectroscopy Facility (ETSF), new, Martin-Luther-Universität Halle Wittenberg (MLU), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Queen Mary University of London (QMUL), and Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)

Subjects
Carbon nanotubes, Collapse (topology), Nanotechnology, 02 engineering and technology, Carbon nanotube, 01 natural sciences, Molecular physics, law.invention, symbols.namesake, [CHIM.GENI]Chemical Sciences/Chemical engineering, law, 0103 physical sciences, Génie chimique, General Materials Science, Tube (fluid conveyance), [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, 010306 general physics, Génie des procédés, Continuum mechanics, Chemistry, General Chemistry, 021001 nanoscience & nanotechnology, Bundle, Raman spectroscopy, symbols, Density-functionaltight-binding, 0210 nano-technology
Abstract

International audience; We study the pressure induced collapse of single-, double- and triple-wall carbon nanotubes. Theoretical simulations were performed using density-functional tight-binding theory. For tube walls separated by the graphitic distance, we show that the radial collapse pressure, Pc, is mainly determined by the diameter of the innermost tube, din and that its value significantly deviates from the usual Pc∝din−3 Lévy-Carrier law. A modified expression, Pcdin−3=α(1−β2∕din2) with α and β numerical parameters, which reduces the collapse pressure for low diameters is proposed. For din ≳ 1.5 nm an enhanced stability is found which may be assigned as due to the bundle intertube geometry-induced interactions. If the inner and outer tubes are separated by larger distances, the collapse process is found to be more complex. High-pressure resonant Raman experiments were performed in double-wall carbon nanotubes having inner and outer diameters averaging 1.5 nm and 2.0 nm, respectively. A modification in the response of the G-band and the disappearance of the radial breathing modes between 2 GPa and 5 GPa indicate the beginning and the end of the radial collapse process. Experimental results are in good agreement with our theoretical predictions, but do not allow to discriminate from those corresponding to a continuum mechanics model.

Published
2017
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5. Connector theory for reusing model results to determine materials properties

Author

Marco Vanzini, Ayoub Aouina, Martin Panholzer, Matteo Gatti, Lucia Reining, LSI - Spectroscopie théorique (ST), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), European Theoretical Spectroscopy Facility (ETSF), Johannes Kepler Universität Linz - Johannes Kepler University Linz [Autriche] (JKU), Uni Software Plus GmbH, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), the Austrian science Fund FWF under Project No. J 3855-N27, and European Project: 320971,EC:FP7:ERC,ERC-2012-ADG_20120216,SEED(2013)

Subjects
electron-gas, kinetic-energy, Computer Science Applications, gradient approximation, Mechanics of Materials, Modeling and Simulation, linear-response, systems, General Materials Science, exchange-energy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], density-functional theory, accurate, nonlocal approximation, expressions
Abstract

The success of Density Functional Theory (DFT) is partly due to that of simple approximations, such as the Local Density Approximation (LDA), which uses results of a model, the homogeneous electron gas, to simulate exchange-correlation effects in real materials. We turn this intuitive approximation into a general and in principle exact theory by introducing the concept of a connector: a prescription how to use results of a model system in order to simulate a given quantity in a real system. In this framework, the LDA can be understood as one particular approximation for a connector that is designed to link the exchange-correlation potentials in the real material to that of the model. Formulating the in principle exact connector equations allows us to go beyond the LDA in a systematic way. Moreover, connector theory is not bound to DFT, and it suggests approximations also for other functionals and other observables. We explain why this very general approach is indeed a convenient starting point for approximations. We illustrate our purposes with simple but pertinent examples.

Published
2022
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6. Robustness of electronic screening effects in electron spectroscopies: example of V$_2$O$_5$

Author

Gorelov, Vitaly, Reining, Lucia, Lambrecht, Walter, Gatti, Matteo, Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), ETSF, European Theoretical Spectroscopy Facility, LSI - Spectroscopie théorique (ST), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Case Western Reserve University [Cleveland], European Theoretical Spectroscopy Facility (ETSF), Synchrotron SOLEIL (SSOLEIL), and Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Computational Physics (physics.comp-ph), Physics - Computational Physics
Abstract

International audience; In bulk and low-dimensional extended systems, the screening of excitations by the electron cloud is a key feature governing spectroscopic properties. Widely used computational approaches, especially in the framework of many-body perturbation theory, such as the GW approximation and the resulting approximate Bethe-Salpeter equation, are explicitly formulated in terms of the screened Coulomb interaction. In the present work we explore the effect of screening in absorption and electron energy loss spectroscopy, concentrating on the effect of local distortions on the screening and elucidating the resulting changes in the various spectra. Using the layered bulk oxide V2O5 as prototype material, we show in which way local distortions affect the screening, and in which way changes in the screening impact electron energy loss and absorption spectra including excitons. We highlight cancellations that make many-body effects in the spectra very robust with respect to structural modifications, while the band structure undergoes significant changes and the nature of the excitations may also be affected. This yields insight concerning the structure-properties relations that are crucial for the use of V2O5 as energy storage material, and more generally, that may be used to optimize the analysis and the calculation of electronic spectra in complex materials.

Published
2022
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7. Localized state and charge transfer in nitrogen-doped graphene

Author

V. Repain, Jérôme Lagoute, Luc Henrard, Cyril Chacon, Yann Girard, Robert Sporken, S. Rousset, Frédéric Joucken, Andrés R. Botello-Méndez, Damien Cabosart, J. Dumont, Bing Zheng, Jean-Christophe Charlier, Yann Tison, UCL - SST/IMCN/NAPS - Nanoscopic Physics, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie des Sufaces et Interfaces (ICSI), Centre National de la Recherche Scientifique (CNRS), Groupe de Physique des Solides (GPS), Aménités et dynamiques des espaces ruraux (UR ADBX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Unité de Physico-Chimie et de Physique des Matériaux (PCPM), Université Catholique de Louvain = Catholic University of Louvain (UCL)-European Theoretical Spectroscopy Facility (ETSF), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), and Université Catholique de Louvain (UCL)-European Theoretical Spectroscopy Facility (ETSF)

Subjects
inorganic chemicals, Materials science, Scanning tunneling spectroscopy, FOS: Physical sciences, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Spectral line, law.invention, Condensed Matter::Materials Science, law, Condensed Matter::Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Physics::Atomic and Molecular Clusters, [CHIM]Chemical Sciences, Physics::Chemical Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Doping, Charge density, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Nitrogen, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, chemistry, Chemical physics, Density functional theory, Atomic physics, Scanning tunneling microscope, 0210 nano-technology, Carbon
Abstract

Nitrogen-doped epitaxial graphene grown on SiC(000?1) was prepared by exposing the surface to an atomic nitrogen flux. Using Scanning Tunneling Microscopy (STM) and Spectroscopy (STS), supported by Density Functional Theory (DFT) calculations, the simple substitution of carbon by nitrogen atoms has been identified as the most common doping configuration. High-resolution images reveal a reduction of local charge density on top of the nitrogen atoms, indicating a charge transfer to the neighboring carbon atoms. For the first time, local STS spectra clearly evidenced the energy levels associated with the chemical doping by nitrogen, localized in the conduction band. Various other nitrogen-related defects have been observed. The bias dependence of their topographic signatures demonstrates the presence of structural configurations more complex than substitution as well as hole-doping., 5 pages, accepted in PRB

Published
2012
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8. Electronic properties of the five principal stackings of boron nitride moiré bilayers

Author

Latil, Sylvain, Amara, Hakim, Sponza, Lorenzo, Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Matériaux et Phénomènes Quantiques (MPQ (UMR_7162)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, ONERA, CNRS, Laboratoire d'étude des microstructures (LEM), ONERA-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), HEP, INSPIRE, Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and European Theoretical Spectroscopy Facility (ETSF)

Subjects
[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [INFO]Computer Science [cs], [INFO] Computer Science [cs], [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS.COND] Physics [physics]/Condensed Matter [cond-mat], [PHYS.QPHY] Physics [physics]/Quantum Physics [quant-ph]
Abstract

12 pages (5.5 main text); 14 figures (5 in main); 4 tables (3 in main). Supplemental materials concatenated to main text; All theoretical calculations on boron nitride moir\'e bilayers report the properties of, at most, two possible stackings which preserve the monolayer hexagonal symmetry (i.e. the invariance upon rotations of 120°). In this work, we demonstrate that, for a given moir\'e periodicity, the same symmetry is respected by five different stackings and not only two as always discussed in literature. We introduce some definitions and an appropriate nomenclature to identify unambiguously the twist angle and the stacking sequence of any BN bilayer with order-3 rotation symmetry. The nomenclature we introduce here and the method to calssify stacking sequences and the angles is completely general and can be applied to homobilayers of any hexagonal 2D materials. Moreover, we produce density functional theory predictions of the electronic structure of each of the five stacking sequences at six different twist angles and discuss the evolution of the gapwidth and band structure and as a function of these parameters. We show that the gap is indirect at any angle and in any stacking and we identify features that are conserved at any angle within the same stacking sequence.

Published
2022

9. Time dependent reduced density matrix functional theory at strong correlation: insights from a two-site Anderson impurity model

Author

Stefano Di Sabatino, Pina Romaniello, Claudio Verdozzi, Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), European Theoretical Spectroscopy Facility (ETSF), new, ANR-18-CE30-0025,PhemSpec,Spectres de photoémission de Quantum Monte Carlo et de la théorie des perturbations à plusieurs corps: le meilleur des deux mondes(2018), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie et Physique Quantiques (LCPQ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
Density matrix, Physics, Work (thermodynamics), Trace (linear algebra), 010304 chemical physics, Time evolution, General Physics and Astronomy, 01 natural sciences, Adiabatic theorem, symbols.namesake, 0103 physical sciences, symbols, Statistical physics, Hilbert transform, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physical and Theoretical Chemistry, 010306 general physics, Adiabatic process, Anderson impurity model, ComputingMilieux_MISCELLANEOUS
Abstract

The one-body density matrix has recently attracted considerable attention as a promising key quantity for the description of systems out of equilibrium. Its time evolution is given in terms of the two-body density matrix, and thus the central challenge is to find approximations to the latter. An extra layer of difficulty is added when dealing with strong electron correlations. In this work, we explore precisely this regime by looking at the two-site Anderson impurity model as a case study. To address the system's dynamics, we use an adiabatic approximation based on the exact ground-state two-body density matrix. We find that this adiabatic extension does not reproduce the exact results even for a slow switch-on of the external perturbation, and we trace back this behavior to the lack of an accurate imaginary part of the adiabatic approximation to the two-body density matrix. The attempt to restore an approximate imaginary part through a Hilbert transform of the real part works well only for very short times, but quickly deteriorates for longer times, with the one-body density matrix being pushed out of its N-representability domain. Our results thus pose an important constraint on practical prescriptions to perform the time evolution of the one-body density matrix.

Published
2021
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10. Delocalization of dark and bright excitons in flat-band materials and the optical properties of V2O5

Author

Vitaly Gorelov, Lucia Reining, Martin Feneberg, Rüdiger Goldhahn, André Schleife, Walter R. L. Lambrecht, Matteo Gatti, Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), new, Otto-von-Guericke-Universität Magdeburg = Otto-von-Guericke University [Magdeburg] (OVGU), University of Illinois at Urbana-Champaign [Urbana], and University of Illinois System

Subjects
[PHYS]Physics [physics], Condensed Matter - Materials Science, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Mechanics of Materials, Modeling and Simulation, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Materials Science, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Computational Physics (physics.comp-ph), Physics - Computational Physics, Computer Science Applications
Abstract

The simplest picture of excitons in materials with atomic-like localization of electrons is that of Frenkel excitons, where electrons and holes stay close together, which is associated with a large binding energy. Here, using the example of the layered oxide V2O5, we show how localized charge-transfer excitations combine to form excitons that also have a huge binding energy but, at the same time, a large electron-hole distance, and we explain this seemingly contradictory finding. The anisotropy of the exciton delocalization is determined by the local anisotropy of the structure, whereas the exciton extends orthogonally to the chains formed by the crystal structure. Moreover, we show that the bright exciton goes together with a dark exciton of even larger binding energy and more pronounced anisotropy. These findings are obtained by combining first principles many-body perturbation theory calculations, ellipsometry experiments, and tight binding modelling, leading to very good agreement and a consistent picture. Our explanation is general and can be extended to other materials.

Published
2022
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12. Comparison of long-range corrected kernels and range-separated hybrids for excitons in solids

Author

Rita Maji, Elena Degoli, Monica Calatayud, Valérie Véniard, Eleonora Luppi, Véniard, Valérie, Università degli Studi di Modena e Reggio Emilia = University of Modena and Reggio Emilia (UNIMORE), Laboratoire de chimie théorique (LCT), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), and European Theoretical Spectroscopy Facility

Subjects
[PHYS]Physics [physics], Condensed Matter - Materials Science, Time dependent density functional theory kernels. LiF Si, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, [PHYS] Physics [physics]
Abstract

The most accurate theoretical method to describe excitons is the solution of the Bethe-Salpeter equation in the GW approximation (GW-BSE). However, because of its computation cost, time-dependent density functional theory (TDDFT) is becoming the alternative approach to GW-BSE to describe excitons in solids. Nowadays, the most efficient strategy to describe optical spectra of solids in TDDFT is to use long-range corrected exchange-correlation kernels on top of GW or scissor-corrected energies. In recent years, a different strategy based on range-separated hybrid functionals started to be developed in the framework of time-dependent generalised Kohn-Sham density functional theory (TDGKSDFT). Here, we compare the performance of long-range corrected kernels with range-separated hybrid functionals for the description of excitons in solids. This comparison has the purpose to weight the pros and cons of using range-separated hybrid functionals, giving new perspectives for theoretical developments of these functionals. We illustrate the comparison for the case of Si and LiF, representative of solid state excitons., 25 pages, 11 figures

Published
2022

13. Robustness of the chiral-icosahedral golden shell I-Au 60 in multi-shell structures

Author

H.-Ch. Weissker, Sean M. Mullins, Robert L. Whetten, Xóchitl López-Lozano, UTSA Department of Physics and Astronomy [San Antonio], The University of Texas at San Antonio (UTSA), Northern Arizona University [Flagstaff], Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), European Theoretical Spectroscopy Facility (ETSF), ANR-14-CE08-0009,FIT SPRINGS,Des Transitions Individuelles aux Résonances Plasmon de Surface dans les Agrégats d'Or et d'Argent(2014), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Fullerene, Nanostructure, Materials science, 010405 organic chemistry, Icosahedral symmetry, Shell (structure), General Physics and Astronomy, Rigidity (psychology), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Symmetry (physics), 0104 chemical sciences, Electronegativity, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Chemical physics, Density functional theory, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract

International audience; Motivated by the recent theoretical discovery [S.-M. Mullins et al., Nat. Commun. 9, 3352 (2018)] of a surprisingly contracted 60-atom hollow shell of chiral-icosahedral symmetry (I-Au60) of remarkable rigidity and electronegativity, we have explored, via first-principles density functional theory calculations, its physico-chemical interactions with internal and external shells, enabling conclusions regarding its robustness and identifying composite forms in which an identifiable I-Au60 structure may be realized as a product of natural or laboratory processes. The dimensions and rigidity of I-Au60 suggest a templating approach; e.g., an Ih-C60 fullerene fits nicely within its interior, as a nested cage. In this work, we have focused on its susceptibility, i.e., the extent to which the unique structural and electronic properties of I-Au60 are modified by incorporation into selected multi-shell structures. Our results confirm that the I-Au60 shell is robustly maintained and protected in various bilayer structures: Ih-C60@I-Au60, Ih-Au32@I-Au2+60, Au60(MgCp)12, and their silver analogs. A detailed analysis of the structural and electronic properties of the selected I-Au60 shell-based nanostructures is presented. We found that the I-Au60 shell structure is quite well retained in several robust forms. In all cases, the I-symmetry is preserved, and the I-Au60 shell is slightly deformed only in the case of the Ih-C60@I-Au60 system. This analysis serves to stimulate and provide guidance toward the identification and isolation of various I-Au60 shell-based nanostructures, with much potential for future applications. We conclude with a critical comparative discussion of these systems and of the implications for continuing theoretical and experimental investigations

Published
2021
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15. Photoemission spectral functions from the three-body Green's function

Author

Gabriele Riva, Timothée Audinet, Matthieu Vladaj, Pina Romaniello, Arjan Berger, European Theoretical Spectroscopy Facility (ETSF), new, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), ANR-18-CE30-0025,PhemSpec,Spectres de photoémission de Quantum Monte Carlo et de la théorie des perturbations à plusieurs corps: le meilleur des deux mondes(2018), and ANR-19-CE30-0011,TRIXS,Description théorique de la diffusion inélastique des rayons X(2019)

Subjects
Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences, General Physics and Astronomy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], ComputingMilieux_MISCELLANEOUS
Abstract

We present an original strategy for the calculation of direct and inverse photo-emission spectra from first principles. The main goal is to go beyond the standard Green's function approaches, such as the $GW$ method, in order to find a good description not only of the quasiparticles but also of the satellite structures, which are of particular importance in strongly correlated materials. To this end we use as a key quantity the three-body Green's function, or, more precisely, its hole-hole-electron and electron-electron-hole parts, and we show how the one-body Green's function, and hence the corresponding spectral function, can be retrieved from it. We show that, contrary to the one-body Green's function, information about satellites is already present in the non-interacting three-body Green's function. Therefore, simple approximations to the three-body self-energy, which is defined by the Dyson equation for the three-body Green's function and which contains many-body effects, can still yield accurate spectral functions. In particular, the self-energy can be chosen to be static which could simplify a self-consistent solution of the Dyson equation. We give a proof of principle of our strategy by applying it to the Hubbard dimer, for which the exact self-energy is available.

Published
2021
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16. The localization spread and polarizability of rings and periodic chains

Author

Celestino Angeli, Gian Luigi Bendazzoli, Stefano Evangelisti, J. Arjan Berger, Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara = University of Ferrara (UniFE), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and European Theoretical Spectroscopy Facility (ETSF)

Subjects
Physics, Finite ring, localization spread, Mathematical analysis, Position operator, General Physics and Astronomy, Second moment of area, FOS: Physical sciences, metallic and insulating behavior, periodic chains, polarizability, NO, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter - Other Condensed Matter, Polarizability, Position (vector), Periodic boundary conditions, PE2_7, Boundary value problem, Physical and Theoretical Chemistry, Quantum, ComputingMilieux_MISCELLANEOUS, localization spread, polarizability, periodic chains, metallic and insulating behavior, Other Condensed Matter (cond-mat.other), PE5_2
Abstract

The localization spread gives a criterion to decide between metallic and insulating behavior of a material. It is defined as the second moment cumulant of the many-body position operator, divided by the number of electrons. Different operators are used for systems treated with open or periodic boundary conditions. In particular, in the case of periodic systems, we use the complex position definition, which was already used in similar contexts for the treatment of both classical and quantum situations. In this study, we show that the localization spread evaluated on a finite ring system of radius R with open boundary conditions leads, in the large R limit, to the same formula derived by Resta and co-workers [C. Sgiarovello, M. Peressi, and R. Resta, Phys. Rev. B 64, 115202 (2001)] for 1D systems with periodic Born–von Karman boundary conditions. A second formula, alternative to Resta’s, is also given based on the sum-over-state formalism, allowing for an interesting generalization to polarizability and other similar quantities.

Published
2021
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17. Clifford Boundary Conditions for Periodic Systems: the Madelung Constant of Cubic Crystals in 1, 2 and 3 Dimensions

Author

J. Arjan Berger, Véronique Brumas, Nicolas Tavernier, Stefano Evangelisti, Gian Luigi Bendazzoli, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), European Theoretical Spectroscopy Facility (ETSF), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and Universita di Bologna

Subjects
Physics, Condensed Matter - Materials Science, 010304 chemical physics, Mathematical analysis, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Clifford torus, Space (mathematics), 01 natural sciences, Madelung constant, Manifold, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, 0103 physical sciences, Supercell (crystal), Periodic boundary conditions, Boundary value problem, Physical and Theoretical Chemistry, 010306 general physics, Topology (chemistry), ComputingMilieux_MISCELLANEOUS
Abstract

In this work we demonstrate the robustness of a real-space approach for the treatment of infinite systems described with periodic boundary conditions that we have recently proposed (Tavernier et al in J Phys Chem Lett 17:7090, 2000). In our approach we extract a fragment, i.e., a supercell, out of the infinite system, and then modifying its topology into the that of a Clifford torus which is a flat, finite and border-less manifold. We then renormalize the distance between two points by defining it as the Euclidean distance in the embedding space of the Clifford torus. With our method we have been able to calculate the reference results available in the literature with a remarkable accuracy, and at a very low computational effort. In this work we show that our approach is robust with respect to the shape of the supercell. In particular, we show that the Madelung constants converge to the same values but that the convergence properties are different. Our approach scales linearly with the number of atoms. The calculation of Madelung constants only takes a few seconds on a laptop computer for a relative precision of about 10 $$^{-6}$$ .

Published
2021
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18. Optical properties of Ag$_{29}$(BDT)$_{12}$(TPP)$_4$ in the VIS and UV and influence of ligand modeling based on real-time electron dynamics

Author

Rajarshi Sinha-Roy, Hans-Christian Weissker, Robert L. Whetten, Xóchitl López-Lozano, Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), UTSA Department of Physics and Astronomy [San Antonio], The University of Texas at San Antonio (UTSA), Northern Arizona University [Flagstaff], ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), ANR-14-CE08-0009,FIT SPRINGS,Des Transitions Individuelles aux Résonances Plasmon de Surface dans les Agrégats d'Or et d'Argent(2014), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Materials science, 010304 chemical physics, Ligand, Time evolution, Aromaticity, Electron dynamics, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Crystallography, chemistry.chemical_compound, chemistry, 0103 physical sciences, Cluster (physics), Molecule, Physical and Theoretical Chemistry, Absorption (chemistry), Benzene
Abstract

We study the optical properties of the $$\hbox {Ag}_{29}$$ (BDT) $$_{12}$$ (TPP) $$_4$$ cluster, the geometry of which is available from experimental structure determination, by means of Fourier-transformed induced densities from real-time (time evolution) calculations of time-dependent density-functional theory. In particular, we demonstrate the influence of the ligands on the optical spectra in the visible region and, even more, in the UV. A strong peak in the UV reminiscent of the spectrum of isolated benzene is found to be caused by the phenyl rings of the TPP ligand molecules. Nonetheless, their absence in the modeling also impacts the absorption in the visible region substantially. By contrast, the aromatic rings of the BDT ligands are more strongly coupled to the silver core and loose the character of independent oscillators; they contribute a much less peaked UV absorption. Our results underline the importance of properly accounting for the full ligands for precise and reliable modeling.

Published
2021
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20. Halogen molecular modifications at high pressure: the case of iodine

Author

Miguel A. L. Marques, Jean-Paul Itié, Silvana Botti, Alain Polian, Emiliano Fonda, Tetsuo Irifune, Jingming Shi, Toru Shinmei, Pierre Lagarde, Alfonso San-Miguel, Anne-Marie Flank, Spectroscopies optiques des matériaux verres, amorphes et à nanoparticules (SOPRANO), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), School of Physics and Electronic Engineering, Jiangsu Normal University (JSNU), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut für Festkörpertheorie und -optik (IFTO), Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], European Theoretical Spectroscopy Facility (ETSF), Martin-Luther-Universität Halle Wittenberg (MLU), Geodynamics Research Center [Ehime], Ehime University [Matsuyama], Earth-Life Science Institute [Tokyo] (ELSI), Tokyo Institute of Technology [Tokyo] (TITECH), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), and Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], 0303 health sciences, Materials science, Hydrogen, Absorption spectroscopy, fungi, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, Iodine, Diatomic molecule, Dissociation (chemistry), 03 medical and health sciences, [SPI]Engineering Sciences [physics], chemistry, Chemical physics, Halogen, Chlorine, Molecule, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, 0210 nano-technology, 030304 developmental biology
Abstract

International audience; Metallization and dissociation are key transformations in diatomic molecules at high densities particularly significant for modeling giant planets. Using X-ray absorption spectroscopy and atomistic modeling, we demonstrate that in halogens, the formation of a connected molecular structure takes place at pressures well below metallization. Here we show that the iodine diatomic molecule first elongates by ∼0.007 Å up to a critical pressure of Pc ∼ 7 GPa, developing bonds between molecules. Then its length continuously decreases with pressure up to 15–20 GPa. Universal trends in halogens are shown and allow us to predict for chlorine a pressure of 42 ± 8 GPa for molecular bond-length reversal. Our findings contribute to tackling the molecule invariability paradigm in diatomic molecular phases at high pressures and may be generalized to other abundant diatomic molecules in the universe, including hydrogen.

Published
2021
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23. Wigner localization in two and three dimensions: an \emph{ab initio} approach

Author

J. Arjan Berger, Estefania Alves, Stefano Evangelisti, Miguel Escobar Azor, European Theoretical Spectroscopy Facility (ETSF), new, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), and ANR-19-CE30-0011,TRIXS,Description théorique de la diffusion inélastique des rayons X(2019)

Subjects
Physics, Strongly Correlated Electrons (cond-mat.str-el), General Physics and Astronomy, FOS: Physical sciences, Function (mathematics), Space (mathematics), 01 natural sciences, 010305 fluids & plasmas, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, symbols.namesake, Condensed Matter - Strongly Correlated Electrons, Classical mechanics, Atomic orbital, 0103 physical sciences, symbols, Periodic boundary conditions, Limit (mathematics), Physical and Theoretical Chemistry, 010306 general physics, Wave function, Translational symmetry, Hamiltonian (quantum mechanics), ComputingMilieux_MISCELLANEOUS
Abstract

In this work, we investigate the Wigner localization of two interacting electrons at very low density in two and three dimensions using the exact diagonalization of the many-body Hamiltonian. We use our recently developed method based on Clifford periodic boundary conditions with a renormalized distance in the Coulomb potential. To accurately represent the electronic wave function, we use a regular distribution in space of Gaussian-type orbitals and we take advantage of the translational symmetry of the system to efficiently calculate the electronic wave function. We are thus able to accurately describe the wave function up to very low density. We validate our approach by comparing our results to a semi-classical model that becomes exact in the low-density limit. With our approach, we are able to observe the Wigner localization without ambiguity.

Published
2021
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24. Photoemission spectra from the Extended Koopman's Theorem, revisited

Author

S. Di Sabatino, J. Koskelo, J. Prodhon, J. A. Berger, M. Caffarel, P. Romaniello, Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie et Physique Quantiques Laboratoire (LCPQ), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche « Matière et interactions » (FeRMI), ANR-18-CE30-0025,PhemSpec,Spectres de photoémission de Quantum Monte Carlo et de la théorie des perturbations à plusieurs corps: le meilleur des deux mondes(2018), and ANR-19-CE30-0011,TRIXS,Description théorique de la diffusion inélastique des rayons X(2019)

Subjects
strong correlation, Work (thermodynamics), Diagonal, FOS: Physical sciences, one-body Green’s function, 02 engineering and technology, 01 natural sciences, Spectral line, RDMFT, Condensed Matter - Strongly Correlated Electrons, Effective energy, 0103 physical sciences, QMC, Statistical physics, 010306 general physics, Link (knot theory), QD1-999, extended Koopman’s theorem, Basis set, ComputingMilieux_MISCELLANEOUS, Original Research, Physics, Strongly Correlated Electrons (cond-mat.str-el), General Chemistry, 021001 nanoscience & nanotechnology, Chemistry, Secular equation, Spectral function, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology, photoemission
Abstract

The Extended Koopman's Theorem (EKT) provides a straightforward way to compute charged excitations from any level of theory. In this work we make the link with the many-body effective energy theory (MEET) that we derived to calculate the spectral function, which is directly related to photoemission spectra. In particular, we show that at its lowest level of approximation the MEET removal and addition energies correspond to the so-called diagonal approximation of the EKT. Thanks to this link, the EKT and the MEET can benefit from mutual insight. In particular, one can readily extend the EKT to calculate the full spectral function, and choose a more optimal basis set for the MEET by solving the EKT secular equation. We illustrate these findings with the examples of the Hubbard dimer and bulk silicon., Comment: 7 pages, 3 figures

Published
2021
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25. Investigating the magnetospheric accretion process in the young pre-transitional disk system DoAr 44 (V2062 Oph): A multiwavelength interferometric, spectropolarimetric, and photometric observing campaign

Author

Catherine Dougados, A. P. Sousa, C. Moutou, Jean-François Donati, Jean-Phillipe Berger, L. M. Rebull, Myriam Benisty, S. H. P. Alencar, K. Pouilly, Jerome Bouvier, Colin P. Folsom, Karine Perraut, Evelyne Alecian, Gilles Duvert, Amelia Bayo, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Universidade de Lisboa = University of Lisbon (ULISBOA), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Spitzer Science Center, California Institute of Technology (CALTECH), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), European Theoretical Spectroscopy Facility (ETSF), new, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), the SPIRou consortium, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Universidade de Lisboa (ULISBOA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)

Subjects
Rotation period, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Magnetosphere, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: pre-main sequence, 01 natural sciences, accretion, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Line (formation), Physics, stars: variables: T Tauri, Photosphere, stars: formation, 010308 nuclear & particles physics, Stellar rotation, accretion disks, Herbig Ae/Be, stars: magnetic field, Astronomy and Astrophysics, Light curve, Accretion (astrophysics), Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Young stars interact with their accretion disk through their strong magnetosphere. We investigate the magnetospheric accretion process in the young stellar system DoAr 44. We monitored the system over several rotational cycles, combining high-resolution optical and near-IR spectropolarimetry with long-baseline near-IR interferometry and multicolor photometry. DoAr 44 is a young 1.2 solar mass star, moderately accreting from its disk, and seen at a low inclination. We derive a rotational period of 2.96 d from the system's light curve. Several optical and near-IR line profiles probing the accretion funnel flows and the accretion shock are modulated at the stellar rotation period. The most variable line profile, HeI 1083 nm, exhibits modulated redshifted wings a signature of accretion funnel flows, as well as deep blueshifted absorptions indicative of transient outflows. The Zeeman-Doppler analysis suggests the star hosts a mainly dipolar magnetic field, inclined by about 20 deg. onto the spin axis, with an intensity reaching about 800 G at the photosphere, and up to 2 +/- 0.8 kG close to the accretion shock. The magnetic field appears strong enough to disrupt the inner disk close to the corotation radius, at a distance of about 4.6 stellar radii (0.043 au). This supports the upper limit of 5 stellar radii (0.047 au) we derived for the size of the magnetosphere from long baseline interferometry. DoAr 44 is a pre-transitional disk system, exhibiting a 25-30 au gap in its circumstellar disk, with the inner and outer disks being misaligned. On a scale of 0.1 au or less, our results indicate that the system steadily accretes from its inner disk through its tilted dipolar magnetosphere. We conclude that in spite of a highly structured outer disk, perhaps the signature of ongoing planetary formation, the magnetospheric accretion process proceeds unimpeded at the star-disk interaction level., Comment: 18 pages, 22 figures, Astronomy & Astrophysics, in press

Published
2020
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26. Optical spectra of 2D monolayers from time-dependent density functional theory

Author

Di Sabatino, Stefano, Berger, Arjan, Romaniello, Pina, Information et Chaos Quantiques (LPT), Laboratoire de Physique Théorique (LPT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, France, Laboratoire de Chimie et Physique Quantiques, Université de Toulouse, CNRS, UPS, France, European Theoretical Spectroscopy Facility (ETSF), and new

Subjects
Physics, Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, Time-dependent density functional theory, 021001 nanoscience & nanotechnology, Polarization (waves), 01 natural sciences, Optical spectra, Spectral line, 3. Good health, Quantum mechanics, 0103 physical sciences, Monolayer, Physical and Theoretical Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

The optical spectra of two-dimensional (2D) periodic systems provide a challenge for time-dependent density-functional theory (TDDFT) because of the large excitonic effects in these materials. In this work we explore how accurately these spectra can be described within a pure Kohn-Sham time-dependent density-functional framework, i.e., a framework in which no theory beyond Kohn-Sham density-functional theory, such as $GW$, is required to correct the Kohn-Sham gap. To achieve this goal we adapted a recent approach we developed for the optical spectra of 3D systems [Cavo, Berger, Romaniello, Phys. Rev. B 101, 115109 (2020)] to those of 2D systems. Our approach relies on the link between the exchange-correlation kernel of TDDFT and the derivative discontinuity of ground-state density-functional theory, which guarantees a correct quasi-particle gap, and on a generalization of the polarization functional [Berger, Phys. Rev. Lett., 115, 137402 (2015)], which describes the excitonic effects. We applied our approach to two prototypical 2D monolayers, $h$-BN and MoS$_2$. We find that our protocol gives a qualitative good description of the optical spectrum of $h$-BN, whereas improvements are needed for MoS$_2$ to describe the intensity of the excitonic peaks., 11 pages, 4 figures

Published
2020
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27. Non-linear response in the cumulant expansion for core hole photoemission

Author

J. J. Kas, Lucia Reining, John J. Rehr, Marilena Tzavala, Department of Physics [Washington], American University Washington D.C. (AU), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), European Theoretical Spectroscopy Facility, ETSF, Palaiseau, France, and affiliation inconnue

Subjects
Physics, GW approximation, Valence (chemistry), Strongly Correlated Electrons (cond-mat.str-el), Equations of motion, FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter - Other Condensed Matter, Nonlinear system, Condensed Matter - Strongly Correlated Electrons, Atomic orbital, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Functional derivative, Density functional theory, Statistical physics, 010306 general physics, 0210 nano-technology, Cumulant, Other Condensed Matter (cond-mat.other)
Abstract

Most currently used approximations for the one-particle Green's function G in the framework of many-body perturbation theory, such as Hedin's GW approximation or the cumulant GW+C approach, are based on a linear response approximation for the screened interaction W. The extent to which such a hypothesis is valid and ways to go beyond have been explored only very little. Here we show how to derive a cumulant Green's function beyond linear-response from the equation of motion of the Green's function in a functional derivative formulation. The results can be written in a compact form, which opens the possibility to calculate the corrections in a first principles framework using time-dependent density functional theory. In order to illustrate the potential importance of the corrections, numerical results are presented for a model system with a core level and two valence orbitals., 9 pages, 1 figure

Published
2020
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28. How metallic are noble-metal clusters? Static screening and polarizability in quantum-sized silver and gold nanoparticles

Author

Hans-Christian Weissker, Rajarshi Sinha-Roy, P. García-González, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), European Theoretical Spectroscopy Facility, and Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC)

Subjects
Materials science, Condensed matter physics, Shell (structure), Coinage metals, Nanoparticle, 02 engineering and technology, engineering.material, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Metal, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Polarizability, visual_art, engineering, visual_art.visual_art_medium, General Materials Science, Noble metal, Surface charge, 0210 nano-technology, Quantum, ComputingMilieux_MISCELLANEOUS
Abstract

Metallicity of nanoparticles can be defined in different ways. One possibility is to look at the degree to which external fields are screened inside the object. This screening would be complete in a classical perfect metal where surface charges arrange on the classical -i.e., abrupt - surface such that no internal fields exist. However, it is obvious that this situation is modified for very small clusters: the surface charges are "smeared out" at the surface, and the screening might be less complete. In the present work we ask the question as to how close small noble-metal clusters are to a classical metal. We show that, indeed, the screening is almost complete (≈96%) already for as little as one atomic layer of the coinage metals, silver and gold alike. At the same time, we show that quantum effects, viz., electronic shell closings and the Friedel-like oscillations of the density, play a role, meaning that the clusters cannot be described solely using the concept of screening in a classical metal.

Published
2020
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29. Plasmonic quantum size effects in silver nanoparticles are dominated by interfaces and local environments

Author

Alfredo Campos, Jean Lermé, Nicolas Troc, Matthias Hillenkamp, Mathieu Kociak, Emmanuel Cottancin, Hans-Christian Weissker, M. Pellarin, Laboratoire de Physique des Solides (LPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Agrégats et nanostructures (AGNANO), Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), European Theoretical Spectroscopy Facility, Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas = University of Campinas (UNICAMP), Brazilian Science Without Borders ‘Special Visiting Scientist’ programme (88881.030488/2013-01), São Paulo Research Foundation (FAPESP, 16/12807-4), ANR-14-CE08-0009,FIT SPRINGS,Des Transitions Individuelles aux Résonances Plasmon de Surface dans les Agrégats d'Or et d'Argent(2014), ANR-10-EQPX-0050,TEMPOS,Microscopie electronique en transmission sur le plateau Palaiseau Orsay Saclay(2010), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), and Universidade Estadual de Campinas (UNICAMP)

Subjects
Physics, Surface plasmon, Physics::Optics, General Physics and Astronomy, Resonance, 01 natural sciences, Electron spectroscopy, Silver nanoparticle, 010305 fluids & plasmas, Complementary experiments, Chemical physics, 0103 physical sciences, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Absorption (electromagnetic radiation), Quantum, Plasmon
Abstract

The physical properties of metals change when their dimensions are reduced to the nano-scale and new phenomena such as the localized surface-plasmon resonance (LSPR) appear. This collective electronic excitation can be tuned over a large spectral range by adapting the material, size and shape. The existing literature is as rich as it is controversial—for example, size-dependent spectral shifts of the LSPR in small metal nanoparticles, induced by quantum effects, are reported to the red, to the blue or entirely absent. Here we report how complementary experiments on size-selected small silver nanoparticles embedded in silica can yield inconsistent results on the same system: whereas optical absorption shows no size effect in the range between only a few atoms and ~10 nm, a clear spectral shift is observed in single-particle electron spectroscopy. Our quantitative interpretation, based on a mixed classical/quantum model, resolves the apparent contradictions, not only within our experimental data, but also in the literature. Our comprehensive model describes how the local environment is the crucial parameter controlling the manifestation or absence of quantum size effects. The origin of size-dependent shifts of surface plasmon resonances in metal nanoparticles has been controversial for decades. A combined experimental and theoretical study on silver samples and their environments now provides a quantitative picture.

Published
2018
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30. Another proof of Gell-Mann and Low's theorem

Author

Molinari, Luca [Dipartimento di Fisica, Universita degli Studi di Milano, INFN, Sezione di Milano, Via Celoria 16, 20133 Milan (Italy) and European Theoretical Spectroscopy Facility (ETSF), 20133 Milan (Italy)]

Published
2007
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31. Reproducibility in G0W0 calculations for solids

Author

RANGEL, Tonatiuh, DEL BEN, Mauro, VARSANO, Daniele, ANTONIUS, Gabriel, BRUNEVAL, Fabien, DA JORNADA, Felipe H., VAN SETTEN, Michiel J., ORHAN, Okan K., O'REGAN, David D., CANNING, Andrew, FERRETTI, Andrea, MARINI, Andrea, RIGNANESE, Gian-Marco, DESLIPPE, Jack, LOUIE, Steven G., NEATON, Jeffrey B., UCL - SST/IMCN/MODL - Modelling, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Physics, University of California, University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), Istituto Nanoscienze [Modena] (CNR NANO), European Theoretical Spectroscopy Facility (ETSF), Service de recherches de métallurgie physique (SRMP), Département des Matériaux pour le Nucléaire (DMN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de la matière condensée et des nanosciences / Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain = Catholic University of Louvain (UCL), new, IMEC (IMEC), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), School of Physics [TCD Dublin], Trinity College Dublin, Computational Research Division [LBNL Berkeley] (CRD), Centro S3, Istituto di Struttura della Materia (CNR-ISM), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), National Energy Research Scientific Computing Center (NERSC), US Department of Energy, We also acknowledge the use of HPC resources from GENCI-CCRT-TGCC(Grants No. 2014-096018), European Project: 824080,H2020,H2020-INFRAEDI-2018-1,POP2(2018), European Project: 676598,H2020,H2020-EINFRA-2015-1,MaX(2015), European Project: 1117545(2011), University of California-University of California, and Consiglio Nazionale delle Ricerche [Roma] (CNR)

Subjects
Condensed Matter - Materials Science, Plane-wave pseudopotential, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, GW calculations, Nuclear & Particles Physics, Reproducibility, cond-mat.mtrl-sci, Mathematical Sciences, [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph], Hardware and Architecture, Information and Computing Sciences, Physical Sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Solids, Convergence
Abstract

Ab initio many-body perturbation theory within the GW approximation is a Green’s function formalism widely used in the calculation of quasiparticle excitation energies of solids. In what has become an increasingly standard approach, Kohn–Sham eigenenergies, generated from a DFT calculation with a strategically-chosen exchange–correlation functional ‘‘starting point’’, are used to construct G and W, and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways to construct the GW self-energy, and these can lead to variations in predicted quasiparticle energies. For example, for ZnO and TiO2, the GW fundamental gaps reported in the literature can vary by more than 1 eV depending on the GW code used. In this work, we calculate and analyze GW quasiparticle (QP) energies of these and other systems with three different GW codes: BerkeleyGW, Abinit and Yambo. Through a systematic analysis of the GW implementation of these three codes, we identify the primary origin of major discrepancies between codes reported in prior literature to be the different implementations the Coulomb divergence in the Fock exchange term and the frequency integration scheme of the GW self-energy. We then eliminate these discrepancies by using common numerical methods and algorithms, demonstrating that the same quasiparticle energies for a given material can be obtained with different codes, within numerical differences ascribable to the technical details of the underling implementations. This work will be important for users and developers in assessing the precision of future GW applications and methods.

Published
2020
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32. ABINIT: Overview and focus on selected capabilities

Author

Marc Torrent, Nicholas A. Pike, Fabien Bruneval, Henrique Pereira Coutada Miranda, Alessandra Romero, Fabio Ricci, Matteo Giantomassi, Alexandre Martin, Xavier Gonze, Yannick Gillet, Massimiliano Stengel, Lucas Baguet, François Bottin, Francesco Naccarato, Benoit Van Troeye, Tonatiuh Rangel, Olivier Gingras, Guido Petretto, Eric Bousquet, Bernard Amadon, Damien Caliste, Cyrus E. Dreyer, D. R. Hamann, Thomas Applencourt, Guillaume Brunin, Jules Denier, Josef W. Zwanziger, Miquel Royo, Gabriel Antonius, Jordan Bieder, Matthieu J. Verstraete, Julia Wiktor, Valentin Planes, Douglas C. Allan, Gérald Jomard, F. Jollet, Sergei Prokhorenko, Gian-Marco Rignanese, Geoffroy Hautier, Michiel van Setten, Michel Côté, Philippe Ghosez, J. Bouchet, UCL - SST/IMCN/MODL - Modelling, West Virginia University [Morgantown], Université Catholique de Louvain = Catholic University of Louvain (UCL), European Theoretical Spectroscopy Facility (ETSF), Skolkovo Institute of Science and Technology [Moscow] (Skoltech), Service de recherches de métallurgie physique (SRMP), Département des Matériaux pour le Nucléaire (DMN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Chalmers University of Technology [Gothenburg, Sweden], National Science Foundation (US), Department of Energy (US), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), Université de Liège, Communauté Française de Belgique, Fonds de Recherche Nature et Technologies (Canada), Natural Sciences and Engineering Research Council of Canada, Agence Nationale de la Recherche (France), Ministerio de Economía, Industria y Competitividad (España), Generalitat de Catalunya, European Research Council, and European Commission

Subjects
GW approximation, Electric fields, General Physics and Astronomy, Electronic bandstructure, Electronic structure, Perturbation theory, 010402 general chemistry, 01 natural sciences, Projector augmented waves, Pseudopotential, Dielectric materials, Van der Waals forces, 0103 physical sciences, Electronic structure methods, Physical and Theoretical Chemistry, Magnetic field perturbations, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Physics, Strongly correlated materials, 010304 chemical physics, Anharmonicity, Many body perturbation theory, Electric field gradients, 0104 chemical sciences, ABINIT, Computational physics, Dynamical mean-field theory, Density functional perturbation theory, Magnetic fields, Raman spectroscopy, Density functional theory, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Strongly correlated material, Orbital magnetization, Van Der Waals interactions
Abstract

Paper published as part of the special topic on Electronic Structure Software, ABINIT is probably the first electronic-structure package to have been released under an open-source license about 20 years ago. It implements density functional theory, density-functional perturbation theory (DFPT), many-body perturbation theory (GW approximation and Bethe–Salpeter equation), and more specific or advanced formalisms, such as dynamical mean-field theory (DMFT) and the “temperaturedependent effective potential” approach for anharmonic effects. Relying on planewaves for the representation of wavefunctions, density, and other space-dependent quantities, with pseudopotentials or projector-augmented waves (PAWs), it is well suited for the study of periodic materials, although nanostructures and molecules can be treated with the supercell technique. The present article starts with a brief description of the project, a summary of the theories upon which ABINIT relies, and a list of the associated capabilities. It then focuses on selected capabilities that might not be present in the majority of electronic structure packages either among planewave codes or, in general, treatment of strongly correlated materials using DMFT; materials under finite electric fields; properties at nuclei (electric field gradient, Mössbauer shifts, and orbital magnetization); positron annihilation; Raman intensities and electro-optic effect; and DFPT calculations of response to strain perturbation (elastic constants and piezoelectricity), spatial dispersion (flexoelectricity), electronic mobility, temperature dependence of the gap, and spin-magnetic-field perturbation. The ABINIT DFPT implementation is very general, including systems with van der Waals interaction or with noncollinear magnetism. Community projects are also described: generation of pseudopotential and PAW datasets, high-throughput calculations (databases of phonon band structure, second-harmonic generation, and GW computations of bandgaps), and the library LIBPAW. ABINIT has strong links with many other software projects that are briefly mentioned., This work (A.H.R.) was supported by the DMREF-NSF Grant No. 1434897, National Science Foundation OAC-1740111, and U.S. Department of Energy DE-SC0016176 and DE-SC0019491 projects. N.A.P. and M.J.V. gratefully acknowledge funding from the Belgian Fonds National de la Recherche Scientifique (FNRS) under Grant No. PDR T.1077.15-1/7. M.J.V. also acknowledges a sabbatical “OUT” grant at ICN2 Barcelona as well as ULiège and the Communauté Française de Belgique (Grant No. ARC AIMED G.A. 15/19-09). X.G. and M.J.V. acknowledge funding from the FNRS under Grant No. T.0103.19-ALPS. X.G. and G.-M. R. acknowledge support from the Communauté française de Belgique through the SURFASCOPE Project (No. ARC 19/24-057). X.G. acknowledges the hospitality of the CEA DAM-DIF during the year 2017. G.H. acknowledges support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (Materials Project Program No. KC23MP). The Belgian authors acknowledge computational resources from supercomputing facilities of the University of Liège, the Consortium des Equipements de Calcul Intensif (Grant No. FRS-FNRS G.A. 2.5020.11), and Zenobe/CENAERO funded by the Walloon Region under Grant No. G.A. 1117545. M.C. and O.G. acknowledge support from the Fonds de Recherche du Québec Nature et Technologie (FRQ-NT), Canada, and the Natural Sciences and Engineering Research Council of Canada (NSERC) under Grant No. RGPIN-2016-06666. The implementation of the libpaw library (M.T., T.R., and D.C.) was supported by the ANR NEWCASTLE project (Grant No. ANR-2010-COSI-005-01) of the French National Research Agency. M.R. and M.S. acknowledge funding from Ministerio de Economia, Industria y Competitividad (MINECO-Spain) (Grants Nos. MAT2016-77100-C2-2-P and SEV-2015-0496) and Generalitat de Catalunya (Grant No. 2017 SGR1506). This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation program (Grant Agreement No. 724529). P.G. acknowledges support from FNRS Belgium through PDR (Grant No. HiT4FiT), ULiège and the Communauté française de Belgique through the ARC project AIMED, the EU and FNRS through M.ERA.NET project SIOX, and the European Funds for Regional Developments (FEDER) and the Walloon Region in the framework of the operational program “Wallonie-2020.EU” through the project Multifunctional thin films/LoCoTED. The Flatiron Institute is a division of the Simons Foundation. A large part of the data presented in this paper is available directly from the Abinit Web page www.abinit.org. Any other data not appearing in this web page can be provided by the corresponding author upon reasonable request.

Published
2020
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33. The Abinit project: Impact, environment and recent developments

Author

Jules Denier, Benoit Van Troeye, Guillaume Brunin, Miguel A. L. Marques, Yann Pouillon, Nicole Helbig, Alessandra Romero, Henrique Pereira Coutada Miranda, Alexandre Martin, William Lafargue-Dit-Hauret, Geoffroy Hautier, Jean-Michel Beuken, Michael Marcus Schmitt, Bernard Amadon, Olivier Gingras, Xavier Gonze, Kurt Lejaeghere, Cyril Martins, Gabriel Antonius, Xu He, Grégory Geneste, Nils Brouwer, Valentin Planes, Frédéric Arnardi, Jordan Bieder, Jean-Baptiste Charraud, J. Bouchet, Francesco Naccarato, Wei Chen, Yongchao Jia, F. Jollet, Kristin A. Persson, Michiel van Setten, Théo Cavignac, Marc Torrent, Fabien Bruneval, Lucas Baguet, Guido Petretto, Michel Côté, Philippe Ghosez, François Bottin, Fabio Ricci, D. R. Hamann, Josef W. Zwanziger, Yannick Gillet, Matthieu J. Verstraete, Gian-Marco Rignanese, Natalie Holzwarth, Sergei Prokhorenko, Eric Bousquet, G. Zérah, Matteo Giantomassi, Stefaan Cottenier, UCL - SST/IMCN/MODL - Modelling, Université Catholique de Louvain = Catholic University of Louvain (UCL), European Theoretical Spectroscopy Facility (ETSF), Skolkovo Institute of Science and Technology [Moscow] (Skoltech), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université du Québec à Trois-Rivières (UQTR), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Mathématiques et de Leurs Applications (CMLA), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), CESAM RU [Liège, Belgium] (Université de liège), Service de recherches de métallurgie physique (SRMP), Département des Matériaux pour le Nucléaire (DMN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université de Montréal (UdeM), Universiteit Gent = Ghent University [Belgium] (UGENT), Department of Physics and Astronomy [Piscataway], Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Wake Forest University, Martin-Luther-Universität Halle Wittenberg (MLU), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Universidad de Cantabria [Santander], West Virginia University [Morgantown], IMEC (IMEC), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Dalhousie University [Halifax], The Abinit team, European Project: CTM2014-5848-1R, and Universiteit Gent = Ghent University (UGENT)

Subjects
first-principles calculation, Abinit, Computer science, Many-Body perturbation theory, General Physics and Astronomy, Basis function, 01 natural sciences, 010305 fluids & plasmas, Software, 0103 physical sciences, Total energy, 010306 general physics, density functional theory, computer.programming_language, business.industry, Python (programming language), electronic structure, ABINIT, Algebra, Hardware and Architecture, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Density functional theory, Computational material science, Cohesive energy, business, computer
Abstract

Abinit is a material- and nanostructure-oriented package that implements density-functional theory (DFT) and many-body perturbation theory (MBPT) to find, from first principles, numerous properties including total energy, electronic structure, vibrational and thermodynamic properties, different dielectric and non-linear optical properties, and related spectra. In the special issue to celebrate the 40th anniversary of CPC, published in 2009, a detailed account of Abinit was included [Gonze et al. (2009)], and has been amply cited. The present article comes as a follow-up to this 2009 publication. It includes an analysis of the impact that Abinit has had, through for example the bibliometric indicators of the 2009 publication. Links with several other computational materials science projects are described. This article also covers the new capabilities of Abinit that have been implemented during the last three years, complementing a recent update of the 2009 article published in 2016. Physical and technical developments inside the abinit application are covered, as well as developments provided with the Abinit package, such as the multibinit and a-tdep projects, and related Abinit organization developments such as AbiPy . The new developments are described with relevant references, input variables, tests, and tutorials. Program summary Program Title: Abinit Program Files doi: http://dx.doi.org/10.17632/csvdrr4d68.1 Licensing provisions: GPLv3 Programming language: Fortran2003, Python Journal reference of previous version: X .Gonze et al, Comput. Phys. Commun. 205 (2016) 106–131 Does the new version supersede the previous version?: Yes. The present 8.10.3 version is now the up-to-date stable version of abinit , and supercedes the 7.10.5 version. Reasons for the new version: New developments Summary of revisions: • Many new capabilities of the main abinit application, related to density-functional theory, density-functional perturbation theory, GW, the Bethe-Salpeter equation, dynamical mean-field theory, etc. • New applications in the package: multibinit (second-principles calculations)and tdep (temperature-dependent properties) Nature of problem: Computing accurately material and nanostructure properties: electronic structure, bond lengths, bond angles, primitive cell, cohesive energy, dielectric properties, vibrational properties, elastic properties, optical properties, magnetic properties, non-linear couplings, electronic and vibrational lifetimes, etc. For large-scale systems, second-principles calculations, building upon the first-principles results, are also possible. Solution method: Software application based on density-functional theory and many-body perturbation theory, pseudopotentials, with plane waves or wavelets as basis functions. Different real-time algorithms are implemented for second-principles calculations.

Published
2020
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34. Lattice vibrations and electronic properties of GaSe nanosheets from first principles

Author

Jamal Barvestani, Ali Soltani Vala, Elena Cannuccia, Friedhelm Bechstedt, Mousa Bejani, Olivia Pulci, NAST, CNR-INFM, European Theoretical Spectroscopy Facility (ETSF), European Theoretical Spectroscopy Facility, Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Physics and Astronomy (miscellaneous), Band gap, Phonon, FOS: Physical sciences, Infrared spectroscopy, Lattice vibration, 02 engineering and technology, 01 natural sciences, Stability (probability), symbols.namesake, 0103 physical sciences, General Materials Science, Perturbation theory, 010306 general physics, Condensed Matter - Materials Science, Settore FIS/03, Condensed matter physics, business.industry, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Semiconductor, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, business, Raman spectroscopy
Abstract

International audience; Electronic properties and lattice dynamics of bulk ɛ-GaSe and one, two, and three tetralayers GaSe are investigated by means of density functional and density functional perturbation theory. The few-tetralayer systems are semiconductors with an indirect nature of the fundamental band gap and a Mexican-hat shape is observed at the top of the valence band. The phonon branch analysis reveals the dynamical stability for all systems considered together with the LO-TO splitting breakdown in two-dimensional systems. In-plane (E) and out-of-plane (A) zone-center lattice vibrations dominate the Raman and IR spectra.

Published
2019
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35. A simple position operator for periodic systems

Author

Stefano Battaglia, Diego Moreno, Stefano Evangelisti, Jorge Berger, Gian Luigi Bendazzoli, Emília Valença Ferreira de Aragão, Nicolas Suaud, Thierry Leininger, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Università degli Studi di Perugia (UNIPG), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Systèmes étendus et magnétisme (LCPQ) (SEM), European Theoretical Spectroscopy Facility (ETSF), Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Physics, Operator (physics), Mathematical analysis, Position operator, FOS: Physical sciences, 02 engineering and technology, Expression (computer science), 021001 nanoscience & nanotechnology, 01 natural sciences, Condensed Matter - Other Condensed Matter, Simple (abstract algebra), [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Thermodynamic limit, Key (cryptography), Periodic boundary conditions, Tensor, 010306 general physics, 0210 nano-technology, Other Condensed Matter (cond-mat.other)
Abstract

We present a position operator that is compatible with periodic boundary conditions (PBC). It is a one-body operator that can be applied in calculations of correlated materials by simply replacing the traditional position vector by the new definition. We show that it satisfies important fundamental as well as practical constraints. To illustrate the usefulness of the PBC position operator we apply it to the localization tensor, a key quantity that is able to differentiate metallic from insulating states. In particular, we show that the localization tensor given in terms of the PBC position operator yields the correct expression in the thermodynamic limit. Moreover, we show that it correctly distinguishes between finite precursors of metals and insulators., 5 pages, 1 figure

Published
2019
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36. Distributed Gaussian orbitals for the description of electrons in an external potential

Author

Léa Brooke, Nicolas Suaud, Pierre-François Loos, Stefano Evangelisti, Alejandro Diaz-Marquez, Thierry Leininger, J. A. Berger, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Systèmes étendus et magnétisme (LCPQ) (SEM), European Theoretical Spectroscopy Facility (ETSF), Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Physics, Work (thermodynamics), Gaussian, Organic Chemistry, Electron, 010402 general chemistry, 01 natural sciences, Quantum chemistry, Catalysis, 0104 chemical sciences, Computer Science Applications, Inorganic Chemistry, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, symbols.namesake, Computational Theory and Mathematics, Atomic orbital, 0103 physical sciences, symbols, Statistical physics, Physical and Theoretical Chemistry, 010306 general physics, Basis set, ComputingMilieux_MISCELLANEOUS
Abstract

In this work, we demonstrate the viability of using distributed Gaussian orbitals as a basis set for the calculation of the properties of electrons subjected to an external potential. We validate our method by studying one-electron systems for which we can compare to exact analytical results. We highlight numerical aspects that require particular care when using a distributedGaussian basis set. In particular, we discuss the optimal choice for the distance between two neighboring Gaussian orbitals. Finally, we show how our approach can be applied to many-electron problems.

Published
2018
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37. Unphysical Discontinuities in GW Methods

Author

Johannes Berger, Pierre-François Loos, Pina Romaniello, Mickaël Véril, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Physics, GW approximation, Chemical Physics (physics.chem-ph), 010304 chemical physics, Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences, Function (mathematics), Classification of discontinuities, Computational Physics (physics.comp-ph), 01 natural sciences, Diatomic molecule, Computer Science Applications, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Discontinuity (linguistics), Condensed Matter - Strongly Correlated Electrons, Atomic orbital, Quantum mechanics, Physics - Chemical Physics, 0103 physical sciences, Quasiparticle, Physical and Theoretical Chemistry, Perturbation theory, 010306 general physics, Physics - Computational Physics, ComputingMilieux_MISCELLANEOUS
Abstract

We report unphysical irregularities and discontinuities in some key experimentally-measurable quantities computed within the GW approximation of many-body perturbation theory applied to molecular systems. In particular, we show that the solution obtained with partially self-consistent GW schemes depends on the algorithm one uses to solve self-consistently the quasi-particle (QP) equation. The main observation of the present study is that each branch of the self-energy is associated with a distinct QP solution, and that each switch between solutions implies a significant discontinuity in the quasiparticle energy as a function of the internuclear distance. Moreover, we clearly observe "ripple" effects, i.e., a discontinuity in one of the QP energies induces (smaller) discontinuities in the other QP energies. Going from one branch to another implies a transfer of weight between two solutions of the QP equation. The case of occupied, virtual and frontier orbitals are separately discussed on distinct diatomics. In particular, we show that multisolution behavior in frontier orbitals is more likely if the HOMO-LUMO gap is small., Comment: 7 pages, 5 figures

Published
2018
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38. TDDFT, excitations and spectroscopy

Author

Olevano, Valerio, Théorie de la Matière Condensée (TMC ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), European Theoretical Spectroscopy Facility (ETSF), Dominik Schaniel, and Theo Woike

Subjects
time-dependent, optical absorption, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, spectroscopy, EELS, TDDFT, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], electronic excitations, IXSS, TDLDA, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018
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39. Revisiting the origin of satellites in core level photoemission of transparent conducting oxides: the case of $n$-doped SnO$_2$

Author

Borgatti, F, Berger, JA, Céolin, D, Zhou, JS, Kas, JJ, Guzzo, M, McConville, CF, Offi, F, Panaccione, G, Regoutz, A, Payne, DJ, Rueff, J-P, Bierwagen, O, White, ME, Speck, JS, Gatti, M, Egdell, RG, Borgatti, Francesco, Berger, J. A., Céolin, Deni, Zhou, Jianqiang Sky, Kas, Joshua J., Guzzo, Matteo, Mcconville, C. F., Offi, Francesco, Panaccione, Giancarlo, Regoutz, Anna, Payne, David J., Rueff, Jean-Pascal, Bierwagen, Oliver, White, Mark E., Speck, James S., Gatti, Matteo, Egdell, Russell G., CNR-Istituto per lo Studio dei Materiali Nanostrutturati, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), European Theoretical Spectroscopy Facility (ETSF), Synchrotron SOLEIL (SOLEIL), Department of Physics, University of Washington, Okayama University, Laboratorio Nazionale TASC (TASC), Consiglio Nazionale delle Ricerche (CNR), Inorganic Chemistry Laboratory [Oxford], University of Oxford [Oxford], Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of California [Santa Barbara] (UCSB), University of California, Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)

Subjects
Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), Electronic, Optical and Magnetic Material, FOS: Physical sciences, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], Condensed Matter Physics, ComputingMilieux_MISCELLANEOUS
Abstract

The longstanding problem of interpretation of satellite structures in core level photoemission spectra of metallic systems with a low density of conduction electrons is addressed using the specific example of Sb-doped SnO$_2$. Comparison of {\it ab initio} many-body calculations with experimental hard X-ray photoemission spectra of the Sn 4$d$ states shows that strong satellites are produced by coupling of the Sn core hole to the plasma oscillations of the free electrons introduced by doping. Within the same theoretical framework, spectral changes of the valence band spectra are also related to dynamical screening effects. These results demonstrate that, for the interpretation of electron correlation features in the core level photoelectron spectra of such narrow-band materials, going beyond the homogeneous electron gas electron-plasmon coupling model is essential., 6 PAGES, 4 FIGURES

Published
2017
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40. Classical and ab Initio Plasmonics Meet at Sub-nanometric Noble Metal Rods

Author

Frank Rabilloud, Hans-Christian Weissker, Antonio I. Fernández-Domínguez, P. García-González, Rajarshi Sinha-Roy, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), European Theoretical Spectroscopy Facility (ETSF), new, Institut Lumière Matière [Villeurbanne] (ILM), Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)

Subjects
Electromagnetics, Ab initio, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, Physics::Atomic and Molecular Clusters, Electrical and Electronic Engineering, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Plasmon, Physics, Mesoscopic physics, Condensed matter physics, Time-dependent density functional theory, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Nanorod, Noble metal, Absorption (chemistry), 0210 nano-technology, Biotechnology
Abstract

Applications of noble metal clusters and nanoparticles in different size ranges abound, from a couple of atoms through mesoscopic sizes. Classical electromagnetics calculations are now employed on smaller and smaller sizes, creating an effervescent dynamic in fields such as plasmonics and approaching the tiny sizes where quantum effects and the atomistic structure of matter play predominant roles. Nonetheless, explicit demonstrations of their merits and limitations are rare. Here we study the optical absorption of subnanometric elongated coinage-metal particles using ab initio and classical electromagnetics methods. The comparison between both approaches reveals that the classical plasmonic frequencies are in astonishing agreement with those predicted by ab initio theory for atomistic three-dimensional rods and quasi-one-dimensional chains, as long as collective surface-plasmon resonances lie far below the onset of d-electron excitations. The physical origin of this striking agreement is clarified through...

Published
2017
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41. Many-body correlations and coupling in benzene-dithiol junctions

Author

Valerio Olevano, Tonatiuh Rangel, Gian-Marco Rignanese, Andrea Ferretti, Institut de la matière condensée et des nanosciences / Institute of Condensed Matter and Nanosciences ( IMCN ), Université Catholique de Louvain ( UCL ), European Theoretical Spectroscopy Facility (ETSF), Istituto di Nanoscienze- CNR, Université Grenoble Alpes ( UGA ), TMC - Théorie de la Matière Condensée, Institut Néel ( NEEL ), Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes [Saint Martin d'Hères]-Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes [Saint Martin d'Hères], GENCI-IDRIS, Institut de la matière condensée et des nanosciences / Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain = Catholic University of Louvain (UCL), Théorie de la Matière Condensée (TMC ), Institut Néel (NEEL), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Molecular junction, Coupling strength, Condensed matter physics, FOS: Physical sciences, Conductance, Dithiol, [ PHYS.COND.CM-GEN ] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Many body, chemistry.chemical_compound, Formalism (philosophy of mathematics), chemistry, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Density functional theory, 010306 general physics, 0210 nano-technology, Benzene
Abstract

Most theoretical studies of nanoscale transport in molecular junctions rely on the combination of the Landauer formalism with Kohn-Sham density functional theory (DFT) using standard local and semilocal functionals to approximate exchange and correlation effects. In many cases, the resulting conductance is overestimated with respect to experiments. Recent works have demonstrated that this discrepancy may be reduced when including many-body corrections on top of DFT. Here we study benzene-dithiol (BDT) gold junctions and analyze the effect of many-body perturbation theory (MBPT) on the calculation of the conductance with respect to different bonding geometries. We find that the many-body corrections to the conductance strongly depend on the metal-molecule coupling strength. In the BDT junction with the lowest coupling, many-body corrections reduce the overestimation on the conductance to a factor two, improving the agreement with experiments. In contrast, in the strongest coupling cases, many-body corrections on the conductance are found to be sensibly smaller and standard DFT reveals a valid approach., Comment: 9 pages, 4 figures

Published
2017
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42. Optical properties of periodic systems within the current-current response framework: pitfalls and remedies

Author

Davide Sangalli, Pina Romaniello, Claudio Attaccalite, Myrta Grüning, Jorge Berger, Dipartimento di Fisica (Milano), Università degli Studi di Milano [Milano] (UNIMI), European Theoretical Spectroscopy Facility (ETSF), Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Queen's University [Belfast] (QUB), Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano = University of Milan (UNIMI), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Condensed Matter - Materials Science, business.industry, Perturbation (astronomy), Lithium fluoride, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, 02 engineering and technology, Conductivity, 021001 nanoscience & nanotechnology, 01 natural sciences, Optical absorption spectra, chemistry.chemical_compound, Semiconductor, chemistry, Quantum mechanics, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Quasiparticle, Sum rule in quantum mechanics, 010306 general physics, 0210 nano-technology, business
Abstract

We compare the optical absorption of extended systems using the density-density and current-current linear response functions calculated within many-body perturbation theory. The two approaches are formally equivalent for a finite momentum $\mathbf{q}$ of the external perturbation. At $\mathbf{q}=\mathbf{0}$, however, the equivalence is maintained only if a small $q$ expansion of the density-density response function is used. Moreover, in practical calculations this equivalence can be lost if one naively extends the strategies usually employed in the density-based approach to the current-based approach. Specifically we discuss the use of a smearing parameter or of the quasiparticle lifetimes to describe the finite width of the spectral peaks and the inclusion of electron-hole interaction. In those instances we show that the incorrect definition of the velocity operator and the violation of the conductivity sum rule introduce unphysical features in the optical absorption spectra of three paradigmatic systems: silicon (semiconductor), copper (metal) and lithium fluoride (insulator). We then demonstrate how to correctly introduce lifetime effects and electron-hole interactions within the current-based approach., Comment: 17 pages, 6 figures

Published
2017
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43. Interpretation of monoclinic hafnia valence electron energy-loss spectra by time-dependent density functional theory

Author

Linda Hung, C. Guedj, N. Bernier, P. Blaise, Valerio Olevano, Francesco Sottile, European Theoretical Spectroscopy Facility (ETSF), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Théorie de la Matière Condensée (NEEL - TMC), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), GENCI-IDRIS, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), and Théorie de la Matière Condensée (TMC )

Subjects
monoclinic, EELS, 02 engineering and technology, Electronic structure, Electron, 7. Clean energy, 01 natural sciences, Molecular physics, DFT, Spectral line, HfO 2, TDDFT, 0103 physical sciences, 010306 general physics, Plasmon, VEELS, Physics, Condensed matter physics, PACS: 77.22.Ch, 79.20.Uv, 71.15.Mb, 71.15.Qe, Time-dependent density functional theory, 021001 nanoscience & nanotechnology, hafnia, Quasiparticle, Density of states, TEM, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Valence electron
Abstract

International audience; We present the valence electron energy-loss spectrum and the dielectric function of monoclinic hafnia (m-HfO$_2$) obtained from time-dependent density-functional theory (TDDFT) predictions and compared to energy-filtered spectroscopic imaging measurements in a high-resolution transmission-electron microscope. Fermi's Golden Rule density-functional theory (DFT) calculations can capture the qualitative features of the energy-loss spectrum, but we find that TDDFT, which accounts for local-field effects, provides nearly quantitative agreement with experiment. Using the DFT density of states and TDDFT dielectric functions, we characterize the excitations that result in the m-HfO$_2$ energy loss spectrum. The sole plasmon occurs between 13-16 eV, although the peaks $\sim$28 and above 40 eV are also due to collective excitations. We furthermore elaborate on the first-principles techniques used, their accuracy, and remaining discrepancies among spectra. More specifically, we assess the influence of Hf semicore electrons (5$p$ and 4$f$) on the energy-loss spectrum, and find that the inclusion of transitions from the 4$f$ band damps the energy-loss intensity in the region above 13 eV. We study the impact of many-body effects in a DFT framework using the adiabatic local-density approximation (ALDA) exchange-correlation kernel, as well as from a many-body perspective using a $GW$-derived electronic structure to account for self-energy corrections. These results demonstrate some cancellation of errors between self-energy and excitonic effects, even for excitations from the Hf $4f$ shell. We also simulate the dispersion with increasing momentum transfer for plasmon and collective excitation peaks.

Published
2016
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44. Exciton band structure in two-dimensional materials

Author

Francesco Sottile, Matteo Gatti, Lorenzo Sponza, Lucia Reining, Christine Giorgetti, Pierluigi Cudazzo, European Theoretical Spectroscopy Facility (ETSF), Nano-Bio Spectroscopy Group, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), European Project: 320971,EC:FP7:ERC,ERC-2012-ADG_20120216,SEED(2013), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
Exciton, Binding energy, FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, Two-dimensional materials, 01 natural sciences, Condensed Matter::Materials Science, chemistry.chemical_compound, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Dispersion (optics), Bound excitons, Coulomb, Graphane, 010306 general physics, Electronic band structure, Biexciton, Physics, Condensed Matter - Materials Science, 73.22-f, 78.20.Bh, 78.67.-n, Condensed matter physics, Condensed Matter - Mesoscale and Nanoscale Physics, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Phosphorene, chemistry, Exciton dispersion, Coulomb interaction, Bethe-Salpeter equations, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], Atomic physics, 0210 nano-technology
Abstract

International audience; Low-dimensional materials differ from their bulk counterpart in many respects. In particular, thescreening of the Coulomb interaction is strongly reduced, which can have important consequencessuch as the significant increase of exciton binding energies. In bulk materials the binding energyis used as an indicator in optical spectra to distinguish different kinds of excitons, but this is notpossible in low-dimensional materials, where the binding energy is large and comparable in size forexcitons of very different localization. Here we demonstrate that the exciton band structure, whichcan be accessed experimentally, instead provides a powerful way to identify the exciton character.By comparing the ab initio solution of the many-body Bethe-Salpeter equation for graphane andsingle-layer hexagonal BN, we draw a general picture of the exciton dispersion in two-dimensionalmaterials, highlighting the different role played by the exchange electron-hole interaction and by theelectronic band structure. Our interpretation is substantiated by a prediction for phosphorene.

Published
2015
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45. Unphysical and Physical Solutions in Many-Body Theories: from Weak to Strong Correlation

Author

Santiago Rigamonti, Pina Romaniello, Lucia Reining, Jorge Berger, Adrian Stan, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Humboldt University Of Berlin, Groupe Méthodes et outils de la chimie quantique (LCPQ) (GMO), Laboratoire de Chimie et Physique Quantiques (LCPQ), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Humboldt-Universität zu Berlin, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), École normale supérieure - Paris (ENS Paris), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)

Subjects
Work (thermodynamics), multiple solutions, Strong interaction, Structure (category theory), FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, 01 natural sciences, 0103 physical sciences, ddc:530, Limit (mathematics), Statistical physics, Perturbation theory, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Physical quantity, Physics, Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), many-body perturbation theory, Function (mathematics), 530 Physik, 021001 nanoscience & nanotechnology, time-dependent density functional theory, Nonlinear system, dynamical mean-field theory, 0210 nano-technology, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Many-body theory is largely based on self-consistent equations that are constructed in terms of the physical quantity of interest itself, for example the density. Therefore, the calculation of important properties such as total energies or photoemission spectra requires the solution of non-linear equations that have unphysical and physical solutions. In this work we show in which circumstances one runs into an unphysical solution, and we indicate how one can overcome this problem. Moreover, we solve the puzzle of when and why the interacting Green's function does not unambiguously determine the underlying system, given in terms of its potential, or non-interacting Green's function. Our results are general since they originate from the fundamental structure of the equations. The absorption spectrum of lithium fluoride is shown as one illustration, and observations in the literature for some widely used models are explained by our approach. Our findings apply to both the weak and strong-correlation regimes. For the strong-correlation regime we show that one cannot use the expressions that are obtained from standard perturbation theory, and we suggest a different approach that is exact in the limit of strong interaction., 5 pages, 3 figures plus supplemental material

Published
2015
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46. Towards time-dependent current-density-functional theory in the non-linear regime

Author

J. M. Escartín, Phuong Mai Dinh, Paul-Gerhard Reinhard, Eric Suraud, Marc Vincendon, Pina Romaniello, Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), European Theoretical Spectroscopy Facility, Institut für Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Apollo - University of Cambridge Repository

Subjects
[PHYS]Physics [physics], Chemistry, General Physics and Astronomy, Time-dependent density functional theory, Moment (mathematics), Nonlinear system, Quantum mechanics, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Density functional theory, Time domain, Statistical physics, Relaxation (approximation), Physical and Theoretical Chemistry, Local-density approximation, Adiabatic process, ComputingMilieux_MISCELLANEOUS
Abstract

Time-Dependent Density-Functional Theory (TDDFT) is a well-established theoretical approach to describe and understand irradiation processes in clusters and molecules. However, within the so-called adiabatic local density approximation (ALDA) to the exchange-correlation (xc) potential, TDDFT can show insufficiencies, particularly in violently dynamical processes. This is because within ALDA the xc potential is instantaneous and is a local functional of the density, which means that this approximation neglects memory effects and long-range effects. A way to go beyond ALDA is to use Time-Dependent Current-Density-Functional Theory (TDCDFT), in which the basic quantity is the current density rather than the density as in TDDFT. This has been shown to offer an adequate account of dissipation in the linear domain when the Vignale-Kohn (VK) functional is used. Here, we go beyond the linear regime and we explore this formulation in the time domain. In this case, the equations become very involved making the computation out of reach; we hence propose an approximation to the VK functional which allows us to calculate the dynamics in real time and at the same time to keep most of the physics described by the VK functional. We apply this formulation to the calculation of the time-dependent dipole moment of Ca, Mg and Na2. Our results show trends similar to what was previously observed in model systems or within linear response. In the non-linear domain, our results show that relaxation times do not decrease with increasing deposited excitation energy, which sets some limitations to the practical use of TDCDFT in such a domain of excitations.

Published
2015
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47. X-ray magnetic circular dichroism study of the RMn12−Fe series with R = Y, Er and Lu

Author

Magali Morales, G. Krill, F. Baudelet, M. Bacmann, Christine Giorgetti, D. Fruchart, Natalia Skryabina, E.K. Hlil, Pierre Wolfers, Marina G. Shelyapina, Faculty of Physics [St Petersburg], St Petersburg State University (SPbU), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), European Theoretical Spectroscopy Facility (ETSF), new, Laboratoire de Cristallographie, Department of physics, and Perm State University

Subjects
Diffraction, Magnetic structure, Chemistry, Magnetic circular dichroism, Mechanical Engineering, Neutron diffraction, Metals and Alloys, 02 engineering and technology, Dichroism, 021001 nanoscience & nanotechnology, Polarization (waves), 01 natural sciences, Crystallography, Magnetization, X-ray magnetic circular dichroism, Mechanics of Materials, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Materials Chemistry, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

The RMn 12− x Fe x series of compounds of ThMn 12 structure type exhibit rather complicated and composition sensitive magnetic properties. In a recent past, systematic neutron diffraction and magnetisation experiments allow to relate the main aspects of the magnetic structures to the polarisation state of the d-band. X-ray magnetic circular dichroism (XMCD) analyses have been undertaken on iron rich compounds with R = Y, Er, and Lu, thus probing the L 2,3 edges of Mn and Fe as well as Er, and the M 4,5 edges of Er. These experiments permit to better understand the local magnetic polarisation of the different interacting orbitals versus temperature and applied field as well as to precise the nature of the magnetic couplings acting between the 3d metals (M).

Published
2004
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48. Quasiparticle excitations in the photoemission spectrum of CuO from first principles: A GW study

Author

C. Rödl, Lucia Reining, Francesco Sottile, European Theoretical Spectroscopy Facility (ETSF), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
Materials science, Condensed matter physics, Condensed Matter::Superconductivity, Spectrum (functional analysis), Quasiparticle, Strongly correlated material, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Condensed Matter Physics, Electronic, Optical and Magnetic Materials
Abstract

International audience; We present ab initio quasiparticle calculations for electronic excitations and the fundamental band gap of the strongly correlated transition-metal oxide CuO using the GW approximation of many-body perturbation theory. Problems related to the suitability of the method for strongly correlated materials and issues of self-consistency are addressed. We explain why quasiparticle self-consistent GW strongly overestimates the band gap of CuO. Apart from the band gap, electron addition and removal spectra in the quasiparticle approximation including lifetime and matrix-element effects are found to be in excellent agreement with the quasiparticle excitations in direct and inverse photoemission data.

Published
2015
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49. Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 due to Photocarrier Doping

Author

Wegkamp, Daniel, Herzog, Marc, Stähler, Julia, Xian, Lede, Gatti, Matteo, Cudazzo, Pierluigi, McGahan, Christina L., Marvel, Robert E., Haglund, Richard F., Rubio, Angel, Wolf, Martin, Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI), Max Planck Society, European Theoretical Spectroscopy Facility (ETSF), Nano-Bio Spectroscopy Group, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Vanderbilt University [Nashville], and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Condensed Matter - Materials Science, Vanadium Compounds, Strongly Correlated Electrons (cond-mat.str-el), Photoelectron Spectroscopy, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Chemical, Oxides, Photochemical Processes, Phase Transition, Condensed Matter - Strongly Correlated Electrons, Condensed Matter::Materials Science, Models, Chemical, Models, ddc:550, Physics::Atomic and Molecular Clusters, Condensed Matter::Strongly Correlated Electrons, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat]
Abstract

Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO2 band gap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructural insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred.

Published
2014
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50. Interplay between structure and electronic properties of layered transition-metal dichalcogenides: Comparing the loss function of 1T and 2H polymorphs

Author

Cudazzo, Pierluigi, Gatti, Matteo, Rubio, Angel, Nano-Bio Spectroscopy Group, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), European Theoretical Spectroscopy Facility (ETSF), Laboratoire des Solides Irradiés (LSI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI), Max Planck Society, Ministerio de Economía y Competitividad (España), Universidad del País Vasco, Eusko Jaurlaritza, European Research Council, European Commission, CEIT and Tecnun, Universidad de Navarra [Pamplona] (UNAV), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)

Subjects
Exciton dispersion, Two-dimensional materials, Exciton dispersion, Bethe-Salpeter equations, Bethe-Salpeter equations, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Two-dimensional materials
Abstract

Transition-metal dichalcogenides (TMD) share the same global layered structure, but distinct polymorphs are characterized by different local coordinations of the transition-metal atoms. Here we compared the 1T and 2H families of metallic TMD, both in the bulk and in the two-dimensional forms. By means of first-principles time-dependent density functional calculations of the loss function, we established the direct connection between the low-energy plasmon properties and the crystal-structure symmetry. The different atomic environments affect the d−d electron-hole excitations, which are prominent at low energies, resulting in distinct in-plane plasmon dispersions in the two families. Conversely, the different periodicity of the plasmon reappearance along the c axis perpendicular to the layers can be used to distinguish the various crystal structures of TMD., We acknowledge financial support from the European Research Council Advanced grant DYNamo (Grant No. ERC- 2010-AdG-267374), Spanish grant (Grant No. 2010-21282-C02-01), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), and European Commission project CRONOS (Grant No. 280879-2). This research was also supported by a Marie Curie FP7 Integration Grant within the Seventh European Union Framework Programme.

Published
2014
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