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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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