Wim Klopper

Karlsruhe Institute of Technology

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Frank Breher

Karlsruhe Institute of Technology

Stefan Bräse

Karlsruhe Institute of Technology

Christof Holzer

Karlsruhe Institute of Technology

Manfred M. Kappes

Karlsruhe Institute of Technology

Martin Nieger

University of Helsinki

Trygve Helgaker

University of Oslo

Sergei Lebedkin

Karlsruhe Institute of Technology

Peter W. Roesky

Karlsruhe Institute of Technology

Angela Bihlmeier

Karlsruhe University of Education

Wolfram Feuerstein

Karlsruhe Institute of Technology

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Karlsruhe Institute of Technology

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Karlsruhe University of Education

Centre National de la Recherche Scientifique

University of Oslo

Heidelberg University

University of Kaiserslautern

Aarhus University

Institute of Inorganic Chemistry of the Slovak Academy of Sciences

Utrecht University

Deutsches Elektronen-Synchrotron DESY

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A comparison of linear and nonlinear correlation factors for basis set limit Møller-Plesset second order binding energies and structures of He2, Be2, and Ne2

The Journal of Chemical Physics (2006)

David P. Tew Wim Klopper

The basis set limit Møller-Plesset second-order equilibrium bond lengths of He2, Be2, and Ne2, accurate to 0.01a0, are computed to be 5.785a0, 5.11a0, and 6.05a0. The corresponding binding energies are 22.4+/-0.1, 2180+/-20, and 86+/-2 muE(h), respectively. An accuracy of 95% in the binding energy requires an aug-cc-pV6Z basis or larger for conventional Møller-Plesset theory. This accuracy is obtained using an aug-cc-pV5Z basis if geminal basis functions with a linear correlation factor are included and with an aug-cc-pVQZ basis if the linear correlation factor is replaced by exp(-gammar(12)) with gamma=1. The correlation factor r(12) exp(-gammar(12)) does not perform as well, describing the atom more efficiently than the dimer. The geminal functions supplement the orbital basis in the description of both the short-range correlation, at electron coalescence, and the long-range dispersion correlation and the values of gamma that give the best binding energies are smaller than those that are optimum for the atom or the dimer. It is important to sufficiently reduce the error due to the resolution of the identity approximation for the three- and four-electron integrals and we recommend the complementary auxiliary basis set method. The effect of both orbital and geminal basis set superposition error must be considered to obtain accurate binding energies with small orbital basis sets. In this respect, we recommend using exp(-gammar(12)) with localized orbitals and the original orbital-variant formalism.

Møller–Plesset perturbation theory

Electronic correlation

Basis (linear algebra)

10.1063/1.2338037

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Citations (74)

Experimental and computational study of the exchange interaction between the V(iii) centers in the vanadium-cyclal dimer

Dalton Transactions (2023)

Andreas Reiß Maximilian Kai Reimann Chengyu Jin Martha Wachter-Lehn Reinhard K. Kremer

[V2(HCyclal)2] is prepared by controlled oxidation of vanadium nanoparticles at 50 °C in toluene. The V(0) nanoparticles are synthesized in THF by reduction of VCl3 with lithium naphthalenide. They exhibit very small particle sizes of 1.2 ± 0.2 nm and a high reactivity (e.g. with air or water). By reaction of V(0) nanoparticles with the azacrown ether H4Cyclal, [V2(HCyclal)2] is obtained with deep green crystals and high yield. The title compound exhibits a V(III) dimer (V⋯V: 304.1(1) pm) with two deprotonated [HCyclal]3- ligands as anions. V(0) nanoparticles as well as the sole coordination of V(III) by a crown ether as the ligand and nitrogen as sole coordinating atom are shown for the first time. Magnetic measurements and computational results point to antiferromagnetic coupling within the V(III) couple, establishing an antiferromagnetic spin S = 1 dimer with the magnetic susceptibility determined by the thermal population of the total spin ranging from ST = 0 to ST = 2.

Reactivity

10.1039/d3dt03243d

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Erratum: “Communication: Symmetry-adapted perturbation theory with intermolecular induction and dispersion energies from the Bethe–Salpeter equation” [J. Chem. Phys. 147, 181101 (2017)]

The Journal of Chemical Physics (2018)

Christof Holzer Wim Klopper

First Page

Bethe–Salpeter equation

10.1063/1.5017007

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High quantum yields under ambient conditions through expansion of the coordination cage of a ruthenium(II)-polypyridine complex

Frank Schramm Velimir Meded Heike Fliegl Karin Fink Olaf Fuhr

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STRUCTURAL INFORMATION INFERENCE FROM LANTHANOID COMPLEXING SYSTEMS: PHOTOLUMINESCENCE STUDIES ON ISOLATED IONS

Jean François Greisch Manfred M. Kappes Detlef Schooss Wim Klopper Jiří Chmela

10.15278/isms.2016.wi09

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Basis-set convergence of the molecular electric dipole moment

The Journal of Chemical Physics (1999)

Asger Halkier Wim Klopper Trygve Helgaker Poul Jo rgensen

The electric dipole moments (μ) of BH and HF are computed in conventional calculations employing different correlation-consistent basis sets at the levels of Hartree–Fock theory, second-order perturbation theory, and coupled cluster theory with single and double excitations, and single and double excitations with a perturbative triples correction. The basis-set convergence of μ is examined by comparison with results obtained with explicitly correlated wave function models. Inclusion of diffuse functions in the basis set is essential for accurate calculations of μ. They speed up the convergence at the Hartree–Fock level significantly and make the convergence at the correlated levels systematic. Once the outer valence regions important for μ are described accurately via the diffuse functions, the convergence at the correlated levels is governed by the interelectronic Coulomb singularity. For the aug-cc-pVXZ basis sets, the correlation contribution to μ follows μXcorr=μlimcorr+aX−3, which is similar to the form for the correlation energy, and extrapolated values based on this form represent a significant improvement on the ordinary basis-set results. Our estimates of the exact dipole moments μe(HF)=1.8037±0.0007 D and μ0(BH)=1.3586±0.0007 D are in excellent agreement with the experimental values μe(HF)=1.803±0.002 D and μ0(BH)=1.27±0.21 D.

Coupled cluster

Basis function

Basis (linear algebra)

Electronic correlation

10.1063/1.480036

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Citations (118)

Ab-initio DFT/TDDFT study of metal porphyrin systems

Heike Fliegl Wim Klopper Teodor Silviu Balaban

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Excited state vibrational coherence in a binuclear metal adduct: wave packet phase dependant molecular fragmentation under variation of ligand size

EPJ Web of Conferences (2019)

Sebastian V. Kruppa Florian Bäppler Christof Holzer Fabian Dietrich Rolf Diller

Ultrafast vibrational coherence with metal-metal stretching mode character is observed for phosphine-bridged d10-d10 complexes of different size, containing the binuclear [Ag2Cl]+ chromophore in an ion trap. Fragmentation pathways are governed by the wave packet's phase.

Chromophore

Fragmentation

10.1051/epjconf/201920509019

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Chemical accuracy from ‘Coulomb hole’ extrapolated molecular quantum-mechanical calculations

Journal of Molecular Structure (2001)

Keld L. Bak Asger Halkier Poul Jørgensen Jeppe Olsen Trygve Helgaker

Basis (linear algebra)

Quantum chemical

Sequence (biology)

Basis function

10.1016/s0022-2860(01)00566-x

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Approaching the basis-set limit of the dRPA correlation energy with explicitly correlated and projector augmented-wave methods

The Journal of Chemical Physics (2022)

Moritz Humer Michael E. Harding Martin Schlipf Amir Taheridehkordi Zoran Sukurma

The direct random-phase approximation (dRPA) is used to calculate and compare atomization energies for the HEAT set and ten selected molecules of the G2-1 set using both plane waves and Gaussian-type orbitals. We describe detailed procedures to obtain highly accurate and well converged results for the projector augmented-wave method as implemented in the Vienna Ab initio Simulation Package as well as the explicitly correlated dRPA-F12 method as implemented in the TURBOMOLE package. The two approaches agree within chemical accuracy (1 kcal/mol) for the atomization energies of all considered molecules, both for the exact exchange as well as for the RPA. The root mean-square deviation is 0.41 kcal/mol for the exact exchange (evaluated using density functional theory orbitals) and 0.33 kcal/mol for exact exchange plus correlation from the RPA.

Random phase approximation

Basis (linear algebra)

Root mean square

10.1063/5.0124019

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Citations (2)