Localized hybrid exchange‐correlation potentials for Kohn–Sham DFT calculations of NMR and EPR parameters

Abstract

AbstractIn contrast to the conventional, nonlocal, and nonmultiplicative implementation of hybrid exchange‐correlation functionals in self‐consistent calculations, the exact‐exchange contribution to the functional has been implemented as a proper local and multiplicative Kohn–Sham potential, using the localized Hartree–Fock approximation to the optimized effective potential. The resulting localized hybrid potentials provide improved performance over nonlocal implementations in density functional theory (DFT) calculations of nuclear shielding constants of main‐group molecules and electronic g‐tensors of 3d transition–metal complexes. Optimum performance of the localized potentials is found at very similar amounts of exact‐exchange admixture for both properties and is almost independent of the “pure‐DFT” exchange and correlation functionals combined with exact exchange. Based on local kinetic energy density, a measure of exact‐exchange admixture is constructed that helps rationalize the relatively large optimal exact‐exchange contributions found. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005