STOCHASTIC LINEAR-MODEL FOR NONADIABATIC CONDENSED PHASE REACTIONS - WEAK-COUPLING LIMIT

Condensed phase nonadiabatic transitions are studied in a semiclassical two state linear model. The effect of condensed phase is modeled by stochastic motion along the classical coordinate and by stochastic fluctuations of parameters of semiclassical Hamiltonian: slopes of diabatic terms, coupling of terms, and coordinate of avoided crossing. In the weak coupling limit simple formulas for nonadiabatic transition rate are derived without any assumptions about the mechanisms of stochastic classical motion and fluctuations of parameters. The rate appears to be independent of the mechanism of motion. The dependence on fluctuating parameters is expressed only through simple averages over parameter distributions, independent of correlation times of fluctuations.