On stochastic formalisms in transition state theory

The simulation of elementary gas-phase reactions in a concentrated bath may be accomplished by a Markoff-chain model. The concept of the state of secular equilibrium, a necessary condition for the existence of rate coefficients local in time, demands that the Markoffian process be modelled using an inhomogeneous Poisson process. Such a Poisson process will possess microcanonical rates which are functions of time. Its simulation can be accomplished by quasi-Monte-Carlo schemes based on low-discrepancy sequences which are also argued here for the computation of the flux integrals over the configurational space within the framework of variational, microcanonical, transition-state theory.