ABSTRACT
Stochastic approaches to the description of the processes of chemical kinetics originate from Kramers’ work in which the overcoming of a one-dimensional potential barrier by a particle in a condensed medium is considered. The initial idea of this approach is to separate only some reaction coordinates, considering the rest of the system as a ‘thermal bath’, rather than to describe in detail the motion of the whole system of interacting particles. The solvent plays an essential dynamic role in the course of the reaction. The coordinates describing the state of the solvent should therefore be considered as dynamic variables along with the coordinates describing the intramolecular state of the reactants. The physically artificial method, that is, the expansion of the functions, is related with the fact that in the one-dimensional problem the transition probability should be calculated only at times smaller than the vibrational period of the system..
