Dynamical corrections to rate theory

Abstract

We discuss the corrections required to incorporate into a rate-theoretic description of diffusion the dynamical processes which cause diffusion jumps to occur prior to the randomization of the system in its new configuration. A calculation is carried through in detail for the case of immediate return jumps which occur prior to randomization. The results establish that rate theory gives correct predictions at sufficiently low temperatures in classical systems. We also discuss the limit in which the coupling between the migrating particle and the lattice is progressively weakened, as in some known cases of surface diffusion. The available evidence favors a description in which dynamical events are broken by frequent, totally randomizing collisions.