The influence of barrier topography on the dynamics of the H + F 2 reaction

Abstract

Classical trajectory calculations on a series of three DIM potential energy surfaces and a standard LEPS surface for the reaction H + F 2 → HF + F are reported. All surfaces have the same features in collinear configurations but differ in the position, height and number of accessible saddle points in bent configurations. The dependence of reaction cross sections, product energy and angular distributions, thermal rate data and reaction mechanism on these features is investigated and discussed. The non-collinear part of the surfaces is of particular interest when it allows for microscopic branching, the various ensuing reaction mechanisms making different contributions to the product property distributions. In particular, a broadening of the HF vibrational distribution together with the appearance of a component extending to very low vibrational levels can arise from reactive encounters passing through a T-shaped transition state.