EVALUATION OF RESONANCE CONTRIBUTIONS TO THERMAL-REACTION RATES USINGQUANTUM FLUX CORRELATION-FUNCTIONS

We consider the evaluation of thermal rate constants using quantum flu x correlation functions for chemical reactions in which metastable sta tes (resonances) play a significant role in the reaction dynamics. The evaluation of rate constants is hindered in this case because of slow ly decaying oscillations in the correlation functions but we show that it is possible to remove these oscillations by projecting the resonan t states from the wave packets used to calculate flux correlation func tions. These projected states do contribute to the reactive flux, but it is not difficult to include for this using the resonance widths. Th e resulting theory thus uses a combination of short time wave packet p ropagation for the direct contribution, and bound-state methods for th e resonant contribution, thereby achieving a balance between the stren gths of time dependent and time independent methods. We illustrate thi s theory through an application to a simple one-dimensional potential.