Journal ArticleDOI
Ground- and excited-state diatomic bond lengths, vibrational levels, and potential-energy curves from conventional and localized Hartree-Fock-based density-functional theory.
Andrew M. Teale,David J. Tozer +1 more
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Ground- and excited-state diatomic bond lengths, vibrational levels, and potential-energy curves are determined using conventional and localized Hartree-Fock (LHF)-based density-functional theory, and agreement is very good for the ground and first excited state, but deteriorates for the higher states.Abstract:
Ground- and excited-state diatomic bond lengths, vibrational levels, and potential-energy curves are determined using conventional and localized Hartree-Fock (LHF)-based density-functional theory. Exchange only and hybrid functionals (with various fractions of exchange) are considered, together with a standard generalized gradient approximation (GGA). Ground-state bond lengths and vibrational wave numbers are relatively insensitive to whether orbital exchange is treated using the conventional or LHF approach. Excited-state calculations are much more sensitive. For a standard fraction of orbital exchange, N2 and CO vertical excitation energies at experimental bond lengths are accurately described by both conventional and LHF-based approaches, providing an asymptotic correction is present. Excited-state bond lengths and vibrational levels are more accurate with the conventional approach. The best quality, however, is obtained with an asymptotically corrected GGA functional. For the ground and lowest four singlet excited states, the GGA mean absolute errors in bond lengths are 0.006 A (0.5%) and 0.011 A (0.8%) for N2 and CO, respectively. Mean absolute errors in fundamental vibrational wavenumbers are 49 cm(-1) (2.7%) and 68 cm(-1) (5.0%), respectively. The GGA potential-energy curves are compared with near-exact Rydberg-Klein-Rees curves. Agreement is very good for the ground and first excited state, but deteriorates for the higher states.read more
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Journal ArticleDOI
Assessment of Several Hybrid DFT Functionals for the Evaluation of Bond Length Alternation of Increasingly Long Oligomers
Denis Jacquemin,Antoine Femenias,Henry Chermette,Ilaria Ciofini,Carlo Adamo,Jean-Marie André,Eric A. Perpète +6 more
TL;DR: The ground-state geometry of nine series of increasingly long oligomers is optimized, using six hybrid density functionals combined with three different atomic basis sets, and the effect of chain conformation on the BLA is studied.
Journal ArticleDOI
Vibrational distributions in N2 with an improved calculation of energy levels using the RKR method
TL;DR: In this article, the potential curve of the N2 ground state ðX 1 R þ g Þ has been accurately reconstructed using the Rydberg- Klein-Rees (RKR) method extrapolated by a Hulburt and Hirschfelder potential for longer internuclear distances.
Journal ArticleDOI
Maps of current density using density-functional methods.
TL;DR: The performance of several density-functional theory (DFT) methods for the calculation of current densities induced by a uniform magnetic field is examined and the maximal modulus is reduced in moving from HF to B3LYP and BLYP, and further reducing in moving to KT3, OEP(B3LYp), and WY(CCSD).
Journal ArticleDOI
Torsional potential of π-conjugated molecules using the localized Hartree–Fock Kohn–Sham exchange potential
Eduardo Fabiano,F. Della Sala +1 more
TL;DR: In this article, the reliability of the localized Hartree-Fock (LHF) Kohn-Sham exchange potential for the description of the torsional potential of π-conjugated molecules was assessed.
Journal ArticleDOI
Exchange methods in Kohn-Sham theory.
Andrew M. Teale,David J. Tozer +1 more
TL;DR: Differences between exchange methods in exchange-only Kohn-Sham theory are highlighted by calculations of diatomic molecule total energies, uncoupled isotropic NMR shieldings, and HOMO-LUMO eigenvalue differences, which exhibit a spatial correlation with the potential differences.
References
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Journal ArticleDOI
Self-Consistent Equations Including Exchange and Correlation Effects
Walter Kohn,L. J. Sham +1 more
TL;DR: In this paper, the Hartree and Hartree-Fock equations are applied to a uniform electron gas, where the exchange and correlation portions of the chemical potential of the gas are used as additional effective potentials.
Journal ArticleDOI
Adiabatic time-dependent density functional methods for excited state properties
Filipp Furche,Reinhart Ahlrichs +1 more
TL;DR: In this paper, the authors present theory, implementation, and validation of excited state properties obtained from time-dependent density functional theory (TDDFT), based on a fully variational expression for the excited state energy, a compact derivation of first order properties is given.
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Density-functional thermochemistry. V. Systematic optimization of exchange-correlation functionals
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TL;DR: In this article, Ciofini et al. used DFT to calculate the correlation energy for Isoelectronic series of atoms by the Line Integral Method (LIM) and to predict the structural and electronic properties of polymeric systems.