Development of density functionals for thermochemical kinetics

TLDR

This makes it a general‑purpose functional whose domain of applicability has been extended to transition states, rather than a specialized functional for kinetics. A density functional theory exchange‑correlation functional for the exploration of reaction mechanisms is proposed. The improvement in BMK rests on the inclusion of the kinetic energy density together with a large value of the exact exchange mixing coefficient. BMK achieves transition‑state barrier accuracy within 2 kcal/mol without compromising equilibrium properties, and the kinetic‑energy density term corrects the excess exact exchange for ground‑state properties, possibly simulating variable exchange.

Abstract

A density functional theory exchange-correlation functional for the exploration of reaction mechanisms is proposed. This functional, denoted BMK (Boese-Martin for Kinetics), has an accuracy in the 2 kcal/mol range for transition state barriers but, unlike previous attempts at such a functional, this improved accuracy does not come at the expense of equilibrium properties. This makes it a general-purpose functional whose domain of applicability has been extended to transition states, rather than a specialized functional for kinetics. The improvement in BMK rests on the inclusion of the kinetic energy density together with a large value of the exact exchange mixing coefficient. For this functional, the kinetic energy density appears to correct "back" the excess exact exchange mixing for ground-state properties, possibly simulating variable exchange.