REACTION-COORDINATE-DEPENDENT FRICTION IN CLASSICAL ACTIVATED BARRIERCROSSING DYNAMICS - WHEN IT MATTERS AND WHEN IT DOESNT

The impact of the symmetry of the reaction-coordinate dependence of th e solvent friction on the thermally activated barrier crossing rate is examined. Possible symmetry forms are defined for the reaction-coordi nate dependence of the solvent friction. The implications in the effec tive Grote-Hynes theory of Voth [J. Chem. Phys. 97, 5908 (1999)] and t he theory recently presented by Haynes, Voth, and Pollak [J, Chem, Phy s. 101, 7811 (1994)] of a spatially antisymmetric solvent friction are illustrated. Surprisingly, no correction to the Kramers-Grote-Hynes t heory for the transmission coefficient is predicted, although an antis ymmetric spatial dependence of the solvent friction is a strong depart ure from the usual spatially independent friction-based generalized La ngevin equation, The results from the analytical theories are compared to numerically exact generalized Langevin equation simulation results for a simple model system and found to agree well for a wide range of damping strengths and friction time scales, confirming the interestin g predictions of these theories. (C) 1995 American Institute of Physic s.