Evaluation of Microcanonical Rate Constants for Biomolecular Reactions by Path Integral Techniques

摘要

One of the important achievements in bimolecular reaction dynamics has been the investigation of state-to-state reaction cross sections as a function of energy of the colliding partners. A new method is proposed for evaluating the microcanonical rate constant (i.e., the rate constant as a function of energy). Using time correlation functions the rate constant is expressed in terms of the matrix elements of the density operator in the coordinate representation. The main objective of this paper is the development of a method to evaluate these matrix elements. This is accomplished by casting the matrix elements into a form that is easily evaluated by path integral techniques. The efficacy of the method is illustrated by obtaining accurate transmission probabilities as a function of energy for a particle tunneling through an Eckart barrier. The application of the method to systems involving many degrees of freedom is discussed; in particular, the method is well suited for the use of Monte Carlo techniques.