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1. Spatial contributions to nuclear magnetic shieldings

Author

Jinger, Rahul Kumar, Fliegl, Heike, Bast, Radovan, Dimitrova, Maria, Lehtola, Susi, and Sundholm, Dage

Subjects
Physics - Chemical Physics, Physics - Computational Physics
Abstract

We develop a methodology for calculating, analyzing and visualizing nuclear magnetic shielding densities, which are calculated from the current density via the Biot-Savart relation. Atomic contributions to nuclear magnetic shielding constants can be estimated within our framework with a Becke partitioning scheme. The new features have been implemented in the GIMIC program and are applied in this work to the study of the $^1$H and $^{13}$C nuclear magnetic shieldings in benzene (C$_6$H$_6$) and cyclobutadiene (C$_4$H$_4$). The new methodology allows a visual inspection of the spatial origins of the positive (shielding) and negative (deshielding) contributions to the nuclear magnetic shielding constant of a single nucleus, something which has not been hitherto easily accomplished. Analysis of the shielding densities shows that diatropic and paratropic current-density fluxes yield both shielding as well as deshielding contributions, as the shielding or deshielding is determined by the direction of the current-density flux with respect to the studied nucleus instead of the tropicity. Becke partitioning of the magnetic shieldings shows that the magnetic shielding contributions mainly originate from the studied atom and its nearest neighbors, confirming the localized character of nuclear magnetic shieldings., Comment: 18 pages, 8 figures, includes supporting information

Published
2020
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2. Benchmarking magnetizabilities with recent density functionals

Author

Lehtola, Susi, Dimitrova, Maria, Fliegl, Heike, and Sundholm, Dage

Subjects
Physics - Chemical Physics
Abstract

We have assessed the accuracy for magnetic properties of a set of 51 density functional approximations, including both recently published as well as already established functionals. The accuracy assessment considers a series of 27 small molecules and is based on comparing the predicted magnetizabilities to literature reference values calculated using coupled cluster theory with full singles and doubles and perturbative triples [CCSD(T)] employing large basis sets. The most accurate magnetizabilities, defined as the smallest mean absolute error, were obtained with the BHandHLYP functional. Three of the six studied Berkeley functionals and the three range-separated Florida functionals also yield accurate magnetizabilities. Also some older functionals like CAM-B3LYP, KT1, BHLYP (BHandH), B3LYP and PBE0 perform rather well. In contrast, unsatisfactory performance was generally obtained with Minnesota functionals, which are therefore not recommended for calculations of magnetically induced current density susceptibilities, and related magnetic properties such as magnetizabilities and nuclear magnetic shieldings. We also demonstrate that magnetizabilities can be calculated by numerical integration of the magnetizability density; we have implemented this approach as a new feature in the gauge-including magnetically induced current method (GIMIC). Magnetizabilities can be calculated from magnetically induced current density susceptibilities within this approach even when analytical approaches for magnetizabilities as the second derivative of the energy have not been implemented. The magnetizability density can also be visualized, providing additional information that is not otherwise easily accessible on the spatial origin of the magnetizabilities., Comment: 22 pages, 4 figures + 25 pages of supporting information

Published
2020
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5. Knowledge Graph Based RDM Solutions

Author

Sack, Harald, primary, Schrade, Torsten, additional, Bruns, Oleksandra, additional, Posthumus, Etienne, additional, Tietz, Tabea, additional, Norouzi, Ebrahim, additional, Waitelonis, Jörg, additional, Fliegl, Heike, additional, Söhn, Linnaea, additional, Tolksdorf, Julia, additional, Jalle Steller, Jonatan, additional, Az´ocar Guzm´an, Abril, additional, Fathalla, Said, additional, Zainul Ihsan, Ahmad, additional, Hofmann, Volker, additional, Sandfeld, Stefan, additional, Fritzen, Felix, additional, Laadhar, Amir, additional, Schimmler, Sonja, additional, and Mutschke, Peter, additional

Published
2023
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8. From Floppy Disks to 5-Star LOD: FAIR Research Infrastructure for NFDI4Culture

Author

Tietz, Tabea, Bruns, Oleksandra, Söhn, Linnaea, Tolksdorf, Julia, Posthumus, Etienne, Steller, Jonatan Jalle, Fliegl, Heike, Norouzi, Ebrahim, Waitelonis, Jörg, Schrade, Torsten, and Sack, Harald

Subjects
Infrastructure, knowledge graphs, Economics, ddc:330, cultural heritage, research data, linked data, research data management, FAIR
Abstract

NFDI4Culture is establishing an infrastructure for research data on material and immaterial cultural heritage in the context of the German National Research Data Infrastructure (NFDI) in compliance with the FAIR principles. The NFDI4Culture Knowledge Graph is developed and integrated with the Culture Information Portal to aggregate diverse and isolated data from the culture research landscape and thereby increase the discoverability, interoperability and reusability of cultural heritage data. This paper presents the research data management strategy in the long-term project NFDI4Culture, which combines a CMS and a Knowledge Graph-based infrastructure to enable an intuitive and meaningful interaction with research resources in the cultural heritage domain.

Published
2023
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16. Tacticity dependence of single chain polymer folding

Author

Danilov, Denis, Sedghamiz, Elaheh, Fliegl, Heike, Frisch, Hendrik, Barner-Kowollik, Christopher, Wenzel, Wolfgang, Danilov, Denis, Sedghamiz, Elaheh, Fliegl, Heike, Frisch, Hendrik, Barner-Kowollik, Christopher, and Wenzel, Wolfgang

Abstract

Precision polymerization techniques offer the exciting opportunity to manufacture single-chain nanoparticles (SCNPs) with intramolecular crosslinks placed in specific positions along the polymer chain. Earlier studies showed that synthetic polymer chains can fold into defined SCNP conformations through a reversible two-state process, similar to that observed for small peptides and proteins-yet far behind in its structural sophistication. While the natural structures of proteins arise from polypeptides of perfectly defined stereochemistry, the role of main-chain stereochemistry on SCNP folding remains largely unexplored. To investigate the effect of tacticity on SCNP architectures, the development of specific simulation strategies is critical to provide reliable data. Herein, we investigate the structural transitions of SCNPs of different stereochemistries, i.e. atactic, syndiotactic and isotactic of various lengths (L = 10 to L = 30) using all-atom Monte-Carlo simulations. The results indicate that structural transitions occur in syndiotactic polymers at lower temperature compared to atactic and isotactic polymer chains. The effect of main chain stereochemistry on the transition temperature was found to be especially pronounced for shorter polymer chains of length L = 10 to L = 20.

Published
2020

20. Spatial Contributions to 1 H NMR Chemical Shifts of Free-Base Porphyrinoids.

Author

Fliegl, Heike, Dimitrova, Maria, Berger, Raphael J. F., and Sundholm, Dage

Subjects
*MAGNETIC shielding, *DESHIELDING (Spectroscopy), *ATOMIC orbitals, *CONSTANTS of integration, *INSPECTION & review
Abstract

A recently developed methodology for calculating, analyzing, and visualizing nuclear magnetic shielding densities is used for studying spatial contributions including ring-current contributions to 1 H nuclear magnetic resonance (NMR) chemical shifts of aromatic and anti-aromatic free-base porphyrinoids. Our approach allows a visual inspection of the spatial origin of the positive (shielding) and negative (deshielding) contributions to the nuclear magnetic shielding constants. Diatropic and paratropic current-density fluxes yield both shielding and deshielding contributions implying that not merely the tropicity of the current density determines whether the contribution has a shielding or deshielding character. Instead the shielding or deshielding contribution is determined by the direction of the current-density flux with respect to the studied nucleus. [ABSTRACT FROM AUTHOR]

Published
2021
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21. First Rational Synthesis of Antiaromatic 5,15‐Dioxaporphyrin and Its β,β‐Linked Dimer Formation upon Oxidation

Author

Nishiyama, Akihide, Fukuda, Masaya, Mori, Shigeki, Furukawa, Ko, Fliegl, Heike, Furuta, Hiroyuki, and Shimizu, Soji

Abstract

5,15‐Dioxaporphyrin was synthesized for the first time by a nucleophilic aromatic substitution reaction of a nickel bis(α,α′‐dibromodipyrrin) complex with benzaldoxime, followed by an intramolecular annulation of the α‐hydroxy‐substituted intermediate. This unprecedented molecule is a 20π‐electron antiaromatic system, in terms of Hückel's rule of aromaticity, because lone pair electrons of oxygen atoms are incorporated into the 18π‐electron conjugated system of the porphyrin. A theoretical analysis based on the gauge‐including magnetically induced current method confirmed its antiaromaticity and a dominant inner ring pathway for the ring current. The unique reactivity of 5,15‐dioxaporphyrin forming a β,β‐linked dimer upon oxidation was also revealed. © 2018 Wiley

Published
2018

31. Accurate computational determination of the binding energy of the SO3·H2O complex.

Author

Fliegl, Heike, Glöß, Andreas, Welz, Oliver, Olzmann, Matthias, and Klopper, Wim

Subjects
*BINDING energy, *CHEMICAL reactions, *METALLIC composites, *FORCE & energy, *ATOMS, *NUCLEAR energy
Abstract

Reliable thermochemical data for the reaction SO3+H2O⇔SO3·H2O (1a) are of crucial importance for an adequate modeling of the homogeneous H2SO4 formation in the atmosphere. We report on high-level quantum chemical calculations to predict the binding energy of the SO3·H2O complex. The electronic binding energy is accurately computed to De=40.9±1.0 kJ/mol=9.8±0.2 kcal/mol. By using harmonic frequencies from density functional theory calculations (B3LYP/cc-pVTZ and TPSS/def2-TZVP), zero-point and thermal energies were calculated. From these data, we estimate D0=-ΔH1a0(0 K)=7.7±0.5 kcal/mol and ΔH1a0(298 K)=-8.3±1.0 kcal/mol. [ABSTRACT FROM AUTHOR]

Published
2006
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32. Coupled-cluster response theory with linear-r12 corrections: The CC2-R12 model for excitation energies.

Author

Fliegl, Heike, Hättig, Christof, and Klopper, Wim

Subjects
*ATOMS, *INTEGRALS, *STOCHASTIC convergence, *MATHEMATICAL functions, *PARTICLES (Nuclear physics), *PHYSICAL & theoretical chemistry, *MOLECULES, *NUCLEAR physics
Abstract

Coupled-cluster response theory for vertical excitation energies within the second-order approximate coupled-cluster singles-and-doubles model CC2, including linear-r12 corrections, is derived and implemented for Ansätze 1 and 2 of R12 theory. An orthonormal auxiliary basis set is used for the resolution-of-the-identity approximation in order to calculate the three- and four-electron integrals needed in R12 theory. The basis set convergence is investigated for a selected set of atoms and small molecules and it is found that in many cases the convergence is not improved. An analysis of the different contributions to excitation energies shows that the present scheme for the construction of the R12 pair functions leads in response theory to an unbalanced description of ground- and excited-state wave functions and needs to be generalized to carry the high accuracy of R12 methods over to response theory. [ABSTRACT FROM AUTHOR]

Published
2006
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33. Coupled-cluster theory with simplified linear-r12 corrections: The CCSD(R12) model.

Author

Fliegl, Heike, Klopper, Wim, and Hättig, Christof

Subjects
*COMPARISON (Psychology), *PARTICLES (Nuclear physics), *PHYSICAL & theoretical chemistry, *PERTURBATION theory, *ATOMS
Abstract

A simplified singles-and-doubles linear-r12 corrected coupled-cluster model, denoted CCSD(R12), is proposed and compared with the complete singles-and-doubles linear-r12 coupled-cluster method CCSD-R12. An orthonormal auxiliary basis set is used for the resolution-of-the-identity approximation to calculate three-electron integrals needed in the linear-r12 Ansatz. Basis-set convergence is investigated for a selected set of atoms and small molecules. In a large basis, the CCSD(R12) model provides an excellent approximation to the full linear-r12 energy contribution, whereas the magnitude of this contribution is significantly overestimated at the level of second-order perturbation theory. [ABSTRACT FROM AUTHOR]

Published
2005
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34. Ridge-tile-like chiral topology: synthesis, resolution, and complete chiroptical characterization of enantiomers of edge-sharing binuclear square planar complexes of Ni(II) bearing achiral ligands

Author

Soloshonok, Vadim A., Ono, Taizo, Ueki, Hisanori, Vanthuyne, Nicolas, Balaban, Teodar Silviu, Burck, Jochen, Fliegl, Heike, Klopper, Wim, Naubron, Jean-Valere, Bui, Tam T.T., Drake, Alex F., and Roussel, Christian

Subjects
Chirality -- Analysis, Alcohol -- Chemical properties, Alcohol, Denatured -- Chemical properties, High performance liquid chromatography -- Usage, Nickel -- Chemical properties, Nickel -- Atomic properties, Nickel -- Optical properties, Chemistry
Abstract

Binuclear square planar Ni(II) complexes, formed by two tridentate ligands with two imine-nitrogens coordinating two nickel atoms, have presented new types of eidge-tile-like chiral compounds that are stable in the appropriate bent conformation. The new compounds with ridge-tile-like chiral topology are shown to be reasonably stable and hence their chemistry, physical properties and applications are analyzed.

Published
2010

35. The Dalton quantum chemistry program system

Author

Aidas, Kestutis, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linus, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pal, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa., Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thomas, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andreas, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Anders, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvinas, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., Sanchez de Merás, Alfredo, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Aidas, Kestuti, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linu, Christiansen, Ove, Cimiraglia, Renzo, Coriani, Sonia, Dahle, Pål, Dalskov, Erik K., Ekström, Ulf, Enevoldsen, Thoma, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Halkier, Asger, Hättig, Christof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Høyvik, Ida-Marie, Iozzi, Maria Francesca, Jansík, Branislav, Jensen, Hans Jørgen Aa, Jonsson, Dan, Jørgensen, Poul, Kauczor, Joanna, Kirpekar, Sheela, Kjærgaard, Thoma, Klopper, Wim, Knecht, Stefan, Kobayashi, Rika, Koch, Henrik, Kongsted, Jacob, Krapp, Andrea, Kristensen, Kasper, Ligabue, Andrea, Lutnæs, Ola B., Melo, Juan I., Mikkelsen, Kurt V., Myhre, Rolf H., Neiss, Christian, Nielsen, Christian B., Norman, Patrick, Olsen, Jeppe, Olsen, Jógvan Magnus H., Osted, Ander, Packer, Martin J., Pawlowski, Filip, Pedersen, Thomas B., Provasi, Patricio F., Reine, Simen, Rinkevicius, Zilvina, Ruden, Torgeir A., Ruud, Kenneth, Rybkin, Vladimir V., Sałek, Pawel, Samson, Claire C. M., de Merás, Alfredo Sánchez, Saue, Trond, Sauer, Stephan P. A., Schimmelpfennig, Bernd, Sneskov, Kristian, Steindal, Arnfinn H., Sylvester-Hvid, Kristian O., Taylor, Peter R., Teale, Andrew M., Tellgren, Erik I., Tew, David P., Thorvaldsen, Andreas J., Thøgersen, Lea, Vahtras, Olav, Watson, Mark A., Wilson, David J. D., Ziolkowski, Marcin, Ågren, Hans, Dipartimento di Chimica, Università degli Studi di Ferrara (UniFE), Centre for Theoretical and Computational Chemistry [Oslo] (CTCC), 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), 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), Department of Physics, Chemistry and Biology, Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam [Amsterdam] (VU), Laboratory of the Department of Oncology (DEPARTMENT OF ONCOLOGY), Herlev and Gentofte Hospital, Norwegian Meteorological Institute [Oslo] (MET), Teoretisk Kemi, Aarhus University [Aarhus], Centre for Biodiversity Dynamics, Norwegian University of Science and Technology [Trondheim] (NTNU), Norwegian University of Science and Technology (NTNU)-Norwegian University of Science and Technology (NTNU), Karlsruhe Institute of Technology (KIT), Department of Theoretical Chemistry, University Düsseldorf, Department of Mathematics, Tokyo University of Science, Institut Jean-Pierre Bourgin (IJPB), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Department of Environmental Engineering, Technical University of Denmark [Lyngby] (DTU), Computer Services Networks and Systems, Università degli Studi di Modena e Reggio Emilia (UNIMORE), Hammersmith Hospital, Imperial College, London, Department of Haematology, Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Centre for Theoretical and Computational Chemistry, University of Tromsø (UiT), Department of Electronics Materials and Devices, Ivanovo State University of Chemistry and Technology, Department of Chemistry [Copenhagen], Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Department of Pharmacology, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California [San Diego] (UC San Diego), University of California-University of California, School of Chemistry, University of Nottingham, UK (UON), Theoretical Chemistry, Royal Institute of Technology [Stockholm] (KTH ), 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), Norwegian Meteorological Institute, Bakke, Vebjørn, Hjertenaes, Eirik, Høyvik, Ida Marie, Jensen, Hans Jørgen A. a., Kjaergaard, Thoma, Lutnaes, Ola B., Sánchez de Merás, Alfredo, Sylvester Hvid, Kristian O., 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), 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
Materials Chemistry2506 Metals and Alloys, Software Focus, Ab initio electronic structure methods structure methods, ab initio calculations, VDP::Mathematics and natural science: 400::Chemistry: 440::Theoretical chemistry, quantum chemistry: 444, Computer Science Applications1707 Computer Vision and Pattern Recognition, Quantum chemistry program, Ab-initio methods, Scientific Software, Quantum Chemistry, Molecular properties, Biochemistry, Algorithms, [Electronic Structure Theory], Algorithm, Molecular propertie, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Computational Chemistry, Computational Mathematic, Faculty of Science, Physical and Theoretical Chemistry, VDP::Matematikk og Naturvitenskap: 400::Kjemi: 440::Teoretisk kjemi, kvantekjemi: 444
Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self-consistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms. © 2013 John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, (CC BY-NC-ND 3.0)

Published
2014

36. Physical Chemistry Chemical Physics / Analysis of the magnetically induced current density of molecules consisting of annelated aromatic and antiaromatic hydrocarbon rings

Author

Sundholm, Dage, Berger, Raphael J. F., and Fliegl, Heike

Abstract

Magnetically induced current susceptibilities and current pathways have been calculated for molecules consisting of two pentalene groups annelated with a benzene (1) or naphthalene (2) moiety. Current strength susceptibilities have been obtained by numerically integrating separately the diatropic and paratropic contributions to the current flow passing planes through chosen bonds of the molecules. The current density calculations provide novel and unambiguous current pathways for the unusual molecules with annelated aromatic and antiaromatic hydrocarbon moieties. The calculations show that the benzene and naphthalene moieties annelated with two pentalene units as in molecules 1 and 2, respectively, are unexpectedly antiaromatic sustaining only a local paratropic ring current around the ring, whereas a weak diatropic current flows around the CH moiety of the benzene ring. For 1 and 2, the individual five-membered rings of the pentalenes are antiaromatic and a slightly weaker semilocal paratropic current flows around the two pentalene rings. Molecules 1 and 2 do not sustain any net global ring current. The naphthalene moiety of the molecule consisting of a naphthalene annelated with two pentalene units (3) does not sustain any strong ring current that is typical for naphthalene. Instead, half of the diatropic current passing the naphthalene moiety forms a zig-zag pattern along the CC bonds of the naphthalene moiety that are not shared with the pentalene moieties and one third of the current continues around the whole molecule partially cancelling the very strong paratropic semilocal ring current of the pentalenes. For molecule 3, the pentalene moieties and the individual five-membered rings of the pentalenes are more antiaromatic than for 1 and 2. The calculated current patterns elucidate why the compounds with formally [4n + 2] -electrons have unusual aromatic properties violating the Hückel -electron count rule. The current density calculations also provide valuable information for interpreting the measured 1H NMR spectra. (VLID)2389980

Published
2016

39. Calculation of magnetically induced currents in hydrocarbon nanorings

Author

Taubert, Stefan, Sundholm, Dage, Juslius, Jonas, Klopper, Wim, and Fliegl, Heike

Subjects
Benzene -- Chemical properties, Hydrocarbons -- Magnetic properties, Hydrocarbons -- Electric properties, Hydrocarbons -- Structure, Naphthalene -- Chemical properties, Nuclear magnetic resonance -- Evaluation, Chemicals, plastics and rubber industries
Published
2008

45. Ab initio calculation of the vibrational and electronic spectra of trans-and cis-azobenzene

Author

Fliegl, Heike, Kohn, Andreas, Hattig, Christof, and Ahlrichs, Reinhart

Subjects
Azo compounds -- Research, Azo compounds -- Chemical properties, Benzene -- Research, Benzene -- Chemical properties, Chemistry
Abstract

Accurate geometries and harmonic force fields for trans- and cis-azobenzene determined by second-order Moller-Plesset perturbation theory is reported. Both isomers report UV spectra calculated using the second-order approximate couple-cluster singles-and-doubles model CC2 with accurate basis sets.

Published
2003

46. Four-component relativistic 31P NMR calculations for trans-platinum(ii) complexes: importance of the solvent and dynamics in spectral simulations.

Author

Castro, Abril C., Fliegl, Heike, Cascella, Michele, Helgaker, Trygve, Repisky, Michal, Komorovsky, Stanislav, Medrano, María Ángeles, Quiroga, Adoración G., and Swart, Marcel

Subjects
*CHEMICAL shift (Nuclear magnetic resonance), *DENSITY functionals, *MOLECULAR dynamics, *SOLVATION
Abstract

We report a combined experimental–theoretical study on the 31P NMR chemical shift for a number of trans-platinum(ii) complexes. Validity and reliability of the 31P NMR chemical shift calculations are examined by comparing with the experimental data. A successful computational protocol for the accurate prediction of the 31P NMR chemical shifts was established for trans-[PtCl2(dma)PPh3] (dma = dimethylamine) complexes. The reliability of the computed values is shown to be critically dependent on the level of relativistic effects (two-component vs. four component), choice of density functionals, dynamical averaging, and solvation effects. Snapshots obtained from ab initio molecular dynamics simulations were used to identify those solvent molecules which show the largest interactions with the platinum complex, through inspection by using the non-covalent interaction program. We observe satisfactory accuracy from the full four-component matrix Dirac–Kohn–Sham method (mDKS) based on the Dirac–Coulomb Hamiltonian, in conjunction with the KT2 density functional, and dynamical averaging with explicit solvent molecules. [ABSTRACT FROM AUTHOR]

Published
2019
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47. The Dalton quantum chemistry program system

Author

Aidas, Kestudis, Angeli, Celestino, Bak, Keld L., Bakken, Vebjørn, Bast, Radovan, Boman, Linus, Chistiansen, Ove, Coriani, Sonia, Dahle, Pål, Dalskov, Eric K., Ekström, Ulf, Enevoldsen, Thomas, Eriksen, Janus J., Ettenhuber, Patrick, Fernández, Berta, Ferrighi, Lara, Fliegl, Heike, Frediani, Luca, Hald, Kasper, Kalkier, Asger, Hättig, Chistof, Heiberg, Hanne, Helgaker, Trygve, Hennum, Alf Christian, Hettema, Hinne, Hjertenæs, Eirik, Høst, Stinne, Melo, Juan Ignacio, and Provasi, Patricio Federico

Subjects
purl.org/becyt/ford/1 [https], COMPUTATIONAL, Física Atómica, Molecular y Química, MOLECULAR, DALTON, Ciencias Físicas, PROGRAM, purl.org/becyt/ford/1.3 [https], CIENCIAS NATURALES Y EXACTAS, PROPERTIES
Abstract

Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational selfconsistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantummechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms. Fil: Aidas, Kestudis. Vilnius University; Lituania Fil: Angeli, Celestino. Universita Di Ferrara; Italia Fil: Bak, Keld L.. University Aarhus; Dinamarca Fil: Bakken, Vebjørn. University Of Oslo; Noruega Fil: Bast, Radovan. KTH Royal Institute of Techology; Suecia Fil: Boman, Linus. EMGS ASA; Noruega Fil: Chistiansen, Ove. Universita Di Ferrara; Italia Fil: Coriani, Sonia. Universita Degli Studi Di Trieste; Italia Fil: Dahle, Pål. Norwegian Computer Center; Noruega Fil: Dalskov, Eric K.. Systematic; Dinamarca Fil: Ekström, Ulf. University Of Oslo; Noruega Fil: Enevoldsen, Thomas. University of Southern Denmark; Dinamarca Fil: Eriksen, Janus J.. University Aarhus; Dinamarca Fil: Ettenhuber, Patrick. University Aarhus; Dinamarca Fil: Fernández, Berta. Universidad de Santiago de Compostela; España Fil: Ferrighi, Lara. University of Norway; Noruega Fil: Fliegl, Heike. University Of Oslo; Noruega Fil: Frediani, Luca. University of Norway; Noruega Fil: Hald, Kasper. Danske Bank; Dinamarca Fil: Kalkier, Asger. CSC Scandihealth; Dinamarca Fil: Hättig, Chistof. Ruhr-universität Bochum; Alemania Fil: Heiberg, Hanne. Norwegian Meterological Institute; Noruega Fil: Helgaker, Trygve. University Of Oslo; Noruega Fil: Hennum, Alf Christian. Norwegian Defence Research Establishment; Noruega Fil: Hettema, Hinne. The University Of Auckland; Nueva Zelanda Fil: Hjertenæs, Eirik. Norwegian University of Science and Technology; Noruega Fil: Høst, Stinne. University Aarhus; Dinamarca Fil: Melo, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina Fil: Provasi, Patricio Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnologica; Argentina

Published
2014

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