Variational transition state theory. Progress report, July 1, 1979-June 30, 1980

Abstract

The variational transition state theory (VTST) of chemical reaction rates has been further developed and two previously developed and one new version have been illustrated and tested by various applications to collinear and three-dimensional reactions of the type A + BC ..-->.. AB + C. The first two versions considered are canonical variational theory (CVT), which is based on curves of free energy of activation as functions of location of the VTST dividing surface, and microcanonical variational theory (..mu..VT), which is based on minimizing the reactive flux through the VTST dividing surface at each total energy. CVT is simpler but ..mu..VT is more accurate. The new theory, improved canonical variational theory (ICVT), is almost as simple as CVT but almost as accurate as ..mu..VT. This has been demonstrated by applications to H, O, F, Cl, and I reacting with H/sub 2/, H reacting with F/sub 2/ and Cl/sub 2/, and various isotopic analogs and model systems. It was also demonstrated that VTST leads to very good agreement with accurate quantal results for several collinear reactions. Another project used VTST to explore the systematics of kinetic isotope effects for three-dimensional reactions. The predictions sometimes differ considerably from those of the conventionalmore » theory.« less