RATE CONSTANTS IN QUANTUM-MECHANICAL SYSTEMS - A RIGOROUS AND PRACTICAL PATH-INTEGRAL FORMULATION FOR COMPUTER-SIMULATIONS

In this letter we present rigorous equations, amenable to computer sim ulations, for using Feynman path integrals to calculate thermal rate c onstants. The quantum mechanical expression for the thermal rate const ant in terms of the derivative of a side-side correlation function dev eloped by Miller, Schwartz and Tromp (J. Chem. Phys. 79 (1983) 4889) i s used. We calculate the side-side correlation function with a discret ized Feynman path integral. The derivative of the side-side correlatio n function is calculated using statistical mechanical free energy pert urbation calculation methods after computing the trace. The theory is illustrated with the Monte Carlo simulation of a free particle. (C) 19 98 Elsevier Science B.V. All rights reserved.