Memory and temperature induced suppression of activated rate processes

Abstract

A detailed study of memory and temperature induced suppression of activated rate processes is presented. Numerical computations demonstrate that long memory in the presence of moderate barriers can induce noticeable deviation of the reaction rate constant from the predictions of the Kramers–Grote–Hynes theory. A canonical variational transition state theory, based on finding the optimized planar dividing surface, is shown to account quantitatively for the observed suppression of the rate. The suppression is associated with an almost perpendicular rotation of the optimal dividing surface away from the usual one. A further generalization of the Pollak–Grabert–Hänggi theory for the Kramers turnover is presented and shown to account for the computed rate constants for the whole range of damping at a fixed bath memory time.