A THEORY FOR THE THERMALLY ACTIVATED RATE-CONSTANT IN SYSTEMS WITH SPATIALLY DEPENDENT FRICTION

An analytic theory is presented for the thermally activated rate const ant in systems which exhibit spatially dependent and time-correlated f riction along the reaction coordinate motion. The theory is valid over the entire range of damping strengths, including in the region of the Kramers turnover. It is compared to the results of computer simulatio ns on a model nonlinear system and excellent agreement is obtained. Th e present work significantly generalizes existing theories for the act ivated rate constant which are based on the generalized Langevin equat ion for the reaction coordinate motion and spatially independent frict ion.