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5 results on '"Loïc Halbert"'

1. Implementation of relativistic coupled cluster theory for massively parallel GPU-accelerated computing architectures

Author

Loïc Halbert, Michal Repisky, Hans Jørgen Aa. Jensen, Lucas Visscher, Anastasios Papadopoulos, Dmitry I. Lyakh, André Severo Pereira Gomes, Johann V. Pototschnig, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam [Amsterdam] (VU), National Center for Computational Sciences, Oak Ridge National Laboratory, Hylleraas Centre for Quantum Molecular Sciences (Hylleraas), Department of Chemistry [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Physico-Chimie Moléculaire Théorique (PCMT), Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark, Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under ContractDE-AC05-00OR22725, French Ministry of Higher Education and Research, region Hauts de France council and European Regional Development Fund (ERDF) project CPER CLIMIBIO, French national supercomputing facilities (grants DARI A0070801859 and Joliot Curie grands challenges 2019 gch0417)., MESONM International Associated Laboratory (LAI) (ANR-16-IDEX-0004), Austrian Science Fund(FWF):J 4177-N36, Research Council of Norway through a Center of Excellence Grant (Grant No. 262695), ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011), ANR-19-CE29-0019,CompRIXS,Calcul de la diffusion inélastique résonante de rayons X pour toute la classification périodique(2019), ANR-16-IDEX-0004,ULNE,ULNE(2016), University of Southern Denmark (SDU), Theoretical Chemistry, and AIMMS

Subjects
Computer science, Dirac (software), FOS: Physical sciences, 010402 general chemistry, 01 natural sciences, Article, Field (computer science), Computational science, Set (abstract data type), Software, Physics - Chemical Physics, 0103 physical sciences, Point (geometry), SDG 7 - Affordable and Clean Energy, Physical and Theoretical Chemistry, Massively parallel, Chemical Physics (physics.chem-ph), 010304 chemical physics, business.industry, 0104 chemical sciences, Computer Science Applications, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Coupled cluster, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Relativistic quantum chemistry, business
Abstract

International audience; In this paper, we report a reimplementation of the core algorithms of relativistic coupled cluster theory aimed at modern heterogeneous high-performance computational infrastructures. The code is designed for efficient parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end. The resulting ExaCorr module is primarily intended for calculations of molecules with one or more heavy elements, as relativistic effects on electronic structure are included from the outset. In the current work, we thereby focus on exact 2-component methods and demonstrate the accuracy and performance of the software. The module can be used as a stand-alone program requiring a set of molecular orbital coefficients as starting point, but is also interfaced to the DIRAC program that can be used to generate these. We therefore also briefly discuss an improvement of the parallel computing aspects of the relativistic self-consistent field algorithm of the DIRAC program.

Published
2021
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2. Relativistic EOM-CCSD for Core-Excited and Core-Ionized State Energies Based on the Four-Component Dirac-Coulomb(-Gaunt) Hamiltonian

Author

Marta L. Vidal, Loïc Halbert, Sonia Coriani, André Severo Pereira Gomes, and Avijit Shee

Subjects
Hamiltonians, Binding energy, chemistry.chemical_element, 7. Clean energy, 01 natural sciences, Chemical calculations, symbols.namesake, Ionization, 0103 physical sciences, Coulomb, Physical and Theoretical Chemistry, Astatine, Approximation, Physics, Energy, 010304 chemical physics, 3. Good health, Computer Science Applications, chemistry, Excited state, Halogen, symbols, Basis sets, Ionization energy, Atomic physics, Hamiltonian (quantum mechanics)
Abstract

We report an implementation of the core-valence separation approach to the four-component relativistic Hamiltonian-based equation-of-motion coupled-cluster with singles and doubles theory (CVS-EOM-CCSD) for the calculation of relativistic core-ionization potentials and core-excitation energies. With this implementation, which is capable of exploiting double group symmetry, we investigate the effects of the different CVS-EOM-CCSD variants and the use of different Hamiltonians based on the exact two-component (X2C) framework on the energies of different core-ionized and -excited states in halogen- (CH3I, HX, and X-, X = Cl-At) and xenon-containing (Xe, XeF2) species. Our results show that the X2C molecular mean-field approach [Sikkema, J.; J. Chem. Phys. 2009, 131, 124116], based on four-component Dirac-Coulomb mean-field calculations (2DCM), is capable of providing core excitations and ionization energies that are nearly indistinguishable from the reference four-component energies for up to and including fifth-row elements. We observe that two-electron integrals over the small-component basis sets lead to non-negligible contributions to core binding energies for the K and L edges for atoms such as iodine or astatine and that the approach based on Dirac-Coulomb-Gaunt mean-field calculations (2DCGM) are significantly more accurate than X2C calculations for which screened two-electron spin-orbit interactions are included via atomic mean-field integrals.

Published
2021
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3. Cover Image, Volume 120, Issue 21

Author

Loïc Halbert, Małgorzata Olejniczak, Valérie Vallet, André Severo Pereira Gomes, Physico-Chimie Moléculaire Théorique (PCMT), Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Centre of New Technologies, University of Warsaw (UW), ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011), and ANR-16-IDEX-0004,ULNE,ULNE(2016)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, 010304 chemical physics, 0103 physical sciences, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, ComputingMilieux_MISCELLANEOUS, 0104 chemical sciences
Abstract

International audience

Published
2020
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4. The DIRAC code for relativistic molecular calculations

Author

Joost N. P. van Stralen, Jon K. Laerdahl, Jógvan Magnus Haugaard Olsen, Hans Jørgen Aagaard Jensen, André Severo Pereira Gomes, Bruno Senjean, Ephraim Eliav, Marta L. Vidal, Stefan Knecht, Małgorzata Olejniczak, Erik D. Hedegård, Kenneth G. Dyall, Malaya K. Nayak, Radovan Bast, Miroslav Iliaš, Roberto Di Remigio, A. Sunaga, Ignacio Agustín Aucar, Elke Faßhauer, Benjamin Helmich-Paris, Trond Saue, Avijit Shee, Timo Fleig, Lucas Visscher, Markus Pernpointner, Christoph R. Jacob, Loïc Halbert, 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), Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry [Tromsø], University of Tromsø (UiT)-University of Tromsø (UiT), Physico-Chimie Moléculaire Théorique (PCMT), Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Centre for Advanced Study at the Norwegian Academy of Science and Letters, The Norwegian Academy of Science and Letters, Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Department of Chemistry and Pharmaceutical Sciences, Instituto de Modelado e Innovación Tecnológica (CONICET), Hylleraas Centre for Quantum Molecular Sciences (Hylleraas), Department of Chemistry [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Dirac Solutions, School of Chemistry, Tel Aviv University [Tel Aviv], Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Division of Theoretical Chemistry, Max-Planck-Institut für Kohlenforschung (Coal Research), Max-Planck-Gesellschaft, Faculty of Natural Sciences, Matej Bel University (UMB), Institute of Physical and Theoretical Chemistry [Braunschweig], Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], Laboratorium für Physikalische Chemie (ETH-LPC), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Department of Microbiology, Oslo University Hospital [Oslo], Centre for Catalysis and Sustainable Chemistry, Department of Chemistry, Technical University of Denmark, Technical University of Denmark [Lyngby] (DTU), Bhabha Atomic Research Centre (BARC), Government of India, Department of Atomic Energy, Centre of New Technologies, University of Warsaw (UW), Kybeidos GmbH, Instituut Lorentz (INSTITUUT LORENTZ), Universiteit Leiden [Leiden], Department of Chemistry [Michigan], Michigan State University [East Lansing], Michigan State University System-Michigan State University System, Department of Chemistry, Tokyo Metropolitan University, Tokyo Metropolitan University [Tokyo] (TMU), French Ministry of Higher Education and Research, region Hauts de France council, and the European Regional Development Fund (ERDF) project CPER CLIMIBIO, Slovak Research and Development Agency and the Scientific Grant Agency, APVV19-0164 and VEGA 1/0562/20, respectively., Financial support from the European Commission (MetEmbed, Project No. 745967) and the Villum Foundation (Young Investigator Program, Grant No. 29412), Financial support from the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant No. 17J02767, and JSPS Overseas Challenge Program for Young Researchers, Grant No. 201880193., Financial support by the Deutsche Forschungsgemeinschaft (DFG)., Funding by the Deutsche Forschungsgemeinschaft (DFG) and the Agence Nationale de la Recherche (ANR) through various programs, This research used resources of the High Performance Computing Center of the Matej Bel University in Banska Bystrica using the HPC infrastructureacquired in Project Nos. ITMS 26230120002 and 26210120002 (Slovak Infrastructure for High Performance Computing) supported by the Research and Development Operational Programme funded by the ERDF, Support by the Research Council of Norway through its Centres of Excellence scheme, Project No. 262695, and through its Mobility Grant scheme, Project No. 261873., Support of the Polish National Science Centre (Grant No. 2016/23/D/ST4/03217)., Support from CONICET by Grant No. PIP 112-20130100361 and FONCYT by Grant No. PICT 2016-2936, Financial support from the Research Council of Norway through its Centres of Excellence scheme(Project No. 262695)., ANR-16-IDEX-0004,ULNE,ULNE(2016), ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011), 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 Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Tel Aviv University (TAU), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Universiteit Leiden, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-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), 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-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Norwegian Academy of Science and Letters, Matej Bel University, Technische Universität Braunschweig [Braunschweig], Theoretical Chemistry, AIMMS, Groupe Méthodes et outils de la chimie quantique (LCPQ) [GMO], Physico-Chimie Moléculaire Théorique [PCMT], and Laboratorium für Physikalische Chemie [ETH-LPC]

Subjects
Física Atómica, Molecular y Química, MOLECULAR PROPERTIES, Field (physics), Ciencias Físicas, Implicit solvation, Dirac (software), ELECTRONIC STRUCTURE, General Physics and Astronomy, FOS: Physical sciences, 010402 general chemistry, 01 natural sciences, Polarizable continuum model, QUANTUM CHEMISTRY SOFTWARE, purl.org/becyt/ford/1 [https], Theoretical physics, Physics - Chemical Physics, 0103 physical sciences, Physical and Theoretical Chemistry, Physics::Chemical Physics, Physics, Chemical Physics (physics.chem-ph), ENVIRONMENTAL EFFECTS, 010304 chemical physics, RELATIVISTIC MOLECULAR CALCULATIONS, Multireference configuration interaction, Propagator, purl.org/becyt/ford/1.3 [https], SDG 10 - Reduced Inequalities, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Coupled cluster, Embedding, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], CIENCIAS NATURALES Y EXACTAS
Abstract

DIRAC is a freely distributed general-purpose program system for 1-, 2- and 4-component relativistic molecular calculations at the level of Hartree--Fock, Kohn--Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, coupled cluster and electron propagator theory. At the self-consistent-field level a highly original scheme, based on quaternion algebra, is implemented for the treatment of both spatial and time reversal symmetry. DIRAC features a very general module for the calculation of molecular properties that to a large extent may be defined by the user and further analyzed through a powerful visualization module. It allows the inclusion of environmental effects through three different classes of increasingly sophisticated embedding approaches: the implicit solvation polarizable continuum model, the explicit polarizable embedding, and frozen density embedding models. DIRAC was one of the earliest codes for relativistic molecular calculations and remains a reference in its field., The following article has been submitted to The Journal of Chemical Physics. After it is published, it will be found at https://aip.scitation.org/toc/jcp/current

Published
2020
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5. Investigating solvent effects on the magnetic properties of molybdate ions () with relativistic embedding

Author

Valérie Vallet, André Severo Pereira Gomes, Małgorzata Olejniczak, and Loïc Halbert

Subjects
Aqueous solution, Materials science, 010304 chemical physics, Scalar (physics), Solvation, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, Molecular physics, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Ion, 0103 physical sciences, Electromagnetic shielding, Physical and Theoretical Chemistry, Solvent effects, Relativistic quantum chemistry, Electronic density
Abstract

We investigate the ability of mechanical and electronic density functional theory‐based embedding approaches to describe the solvent effects on nuclear magnetic resonance (NMR) shielding constants of the 95Mo nucleus in the molybdate ion in aqueous solution. From the description obtained from calculations with two‐ and four‐component relativistic Hamiltonians, we find that, for such systems, spin‐orbit coupling effects are clearly important for absolute shielding values, but for relative quantities, a scalar relativistic treatment provides sufficient estimation of the solvent effects. We find that the electronic contributions to the solvent effects are relatively modest yet decisive to provide a more accurate magnetic response of the system when compared to reference supermolecular calculations. We analyze the errors in the embedding calculations by statistical methods, as well as through a real‐space representation of NMR shielding densities, which are shown to provide a clear picture of the physical processes at play.

Published
2020
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