An efficient Monte Carlo method for calculating ab initio transition state theory reacton rates in solution

摘要

In this article,we propose an efficient method for sampling the relevant state space in condensed phase reactions.In the present method,the reaction is described by solving the electronic Schrodinger equation for the solute atoms in the presence of explicit solvent molecules.The sampling algorithm uses a molecular mechanics guiding potential in combination with simulated tempering ideas and allows throough exporation of the solvent state space in the context of an ab initio calculation even when the dielectric relaxation time of the solvent is long.The method is applied to the study of he double-proton transfer reaction that takes place between a molecule of acetic acid and a molecule of methanol in tetrahydrofuran.It is demonstrated that calculations of rates of chemical transformations occurring in solovents of medium polarity can be performed with an increase in the cpu time of factors ranging from 4 to 15 with respect to gas-phase calculations.