Localized hybrid exchange-correlation potentials for kohn-Sham DFT calculations of NMR and EPR parameters

Abstract

In contrast to the conventional, nonlocal, and nonmultiplicative implementation of hybrid exchange-correlation functional 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 functional 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.