A PATH-INTEGRAL STUDY OF ELECTRONIC POLARIZATION AND NONLINEAR COUPLING EFFECTS IN CONDENSED-PHASE PROTON-TRANSFER REACTIONS

Feynman path integral quantum transition state theory is used to calculate the quantum rate constants for model proton transfer systems in a polar fluid. The effects of intramolecular vibrations on the proton transfer rate, as well as those from solute and solvent electronic polarization, are examined. In the latter study, quantum Drude oscillators are used to model the high frequency electronic polarization of the solvent and a path integral action functional is developed within the context of that model. The results obtained with the corresponding classical Drude model are compared with the correct quantum treatment. From these calculations, it is concluded that proton transfer reactions involving a significant degree of tunneling cannot be quantitatively described without a quantum mechanical polarizable solvent model. Furthermore, the calculations illustrate the intrinsically nonlinear character of the proton tunneling process in polar solvents.