CURVE CROSSING FORMULATION FOR PROTON-TRANSFER REACTIONS IN SOLUTION

A Landau-Zener curve crossing formulation is developed for proton tran sfer rate constants over the range of proton coupling. This approach s pans the weak coupling regime, where the transfer is a nonadiabatic pr oton tunneling, to the strong coupling regime, where at the reaction t ransition state the proton motion is a quantized vibration lying above the barrier in the proton coordinate. The theory requires that there is strong coupling of the proton transfer solute to the surrounding po lar solvent and includes the influence of the vibrational motion of th e heavy particles between which the proton transfers, Analytic formula s are given for the rate constants in various limits of the proton cou pling strength and the vibrational frequency of the heavy particle mot ion.