Role of inertial and non-Markovian effects on activated barrier crossing dynamics for charge transfer reactions in solution

Charge transfer processes in a polar solvent, modeled as an activated crossing over a parabolic potential barrier, are studied here through the Grote-Hynes (G-H) theory using the recent microscopic approaches to the dielectric friction based on mode coupling theory. The calculated frequency-dependent friction consisting of the short-range as well as the long-range contributions is used to obtain the barrier crossing rates based on the G-H theory, and for comparison also Kramers' theory using the zero-frequency value of the friction. The effect of considering the inertial and non-Markovian motion of the solvent molecules on the calculated friction as well as the barrier crossing rates is investigated. The inertial component of solvent motion is found to be an important factor. (C) 2000 Published by Elsevier Science B.V. All rights reserved.