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@article{218352,
author = {Munzarová, Markéta and Kaupp, Martin},
article_number = {48},
keywords = {Coupled-Cluster methods; density functional theory; EPR parameters; hyperfine coupling constants; transition metal complexes},
language = {eng},
issn = {1089-5639},
journal = {J. Phys. Chem.},
title = {A Critical Validation of Density Functional and Coupled-Cluster Approaches for the Calculation of EPR Hyperfine Coupling Constants in Transition Metal Complexes},
volume = {103},
year = {1999}
}
TY - JOUR
ID - 218352
AU - Munzarová, Markéta - Kaupp, Martin
PY - 1999
TI - A Critical Validation of Density Functional and Coupled-Cluster Approaches for the Calculation of EPR Hyperfine Coupling Constants in Transition Metal Complexes
JF - J. Phys. Chem.
VL - 103
IS - 48
SP - 9966
EP - 9966
PB - American Chemical Society
SN - 10895639
KW - Coupled-Cluster methods
KW - density functional theory
KW - EPR parameters
KW - hyperfine coupling constants
KW - transition metal complexes
N2 - The performance of various density functional approaches for the calculation of electron paramagnetic resonance (EPR) hyperfine coupling constants in transition metal complexes has been evaluated critically by comparison with experimental data and high-level coupled-cluster results for 21 systems, representing a large variety of different electronic situations. While both gradient-corrected and hybrid functionals allow the calculation of isotropic metal hyperfine coupling constants to within ca. 10-15% for the less critical cases (e.g., ScO, TiN, TiO, VO, MnO, MnF), none of the functionals investigated performs well for all complexes. Gradient-corrected functionals tend to underestimate the important core-shell spin polarization. While this may be improved by exact-exchange mixing in some cases, the accompanying spin contamination may even lead to a deterioration of the results for other complexes. We also identify cases, where essentially none of the functionals performs satisfactorily. In the absence of a "universal functional", the functionals to be applied to the calculation of hyperfine couplings in certain areas of transition metal chemistry have to be carefully selected. Desirable, improved functionals should provide sufficiently large spin polarization for core and valence shells without exaggerating it for the latter (and thus introducing spin contamination). Coupling anisotropies and coupling constants for ligand nuclei are also discussed. The computationally much more demanding coupled cluster (CCSD and CCSD(T)) methods, which have been applied to a subset of complexes, show good performance, even when a UHF reference wave function is moderately spin-contaminated.
ER -
MUNZAROVÁ, Markéta a Martin KAUPP. A Critical Validation of Density Functional and Coupled-Cluster Approaches for the Calculation of EPR Hyperfine Coupling Constants in Transition Metal Complexes. \textit{J. Phys. Chem.}. American Chemical Society, 1999, roč.~103, č.~48, s.~9966-9982. ISSN~1089-5639.
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