Thermal rate constants for resonance-supporting reaction barriers by the flux averaging method

The flux averaging method which was introduced in order to calculate transmission probabilities in resonant tunneling processes is reformulated for calculations of thermal rate constants for reactions with long-lived intermediate states, associated with quantum resonances. The rate constant is expressed as a time-dependent weighted average of time integrals over different flux-flux correlation functions. This exact expression for the rate is shown to converge to its asymptotic value within the 'direct' dynamics timescale, regardless of the population of long-lived resonance states. The method is derived and demonstrated for symmetric and non-symmetric resonance-supporting double-barrier potentials. (C) 2003 Elsevier Science B.V. All rights reserved.