NONEQUILIBRIUM FREE-ENERGY SURFACES FOR HYDROGEN-BONDED PROTON-TRANSFER COMPLEXES IN SOLUTION

A theory is presented for the electronic structure and multidimensional free energy surfaces for hydrogen-bonded complexes AH...B capable of proton transfer to form an ion pair A-...HB+ in solution. Two diabatic states, neutral and ionic, are electronically coupled to each other and electrostatically coupled to the surrounding solvent and are treated via a nonlinear Schrodinger equation approach. The theory includes nonequilibrium solvation of the complex, a feature important for proton-transfer dynamics and spectroscopic phenomena. Representative calculations for a model OH...N complex are presented. The importance of the solvent polarization for the electronic structure of the complex is illustrated by comparison with the results obtained by solvation of the in vacuo electronic structure.