A model for combined electron and proton transfer in electrochemical systems

We propose a model Hamiltonian for electrochemical electron and proton transfer; it contains terms for the two transfer steps themselves and for their coupling to solvent and vibrational modes. As first applications, we present potential-energy surfaces for the case where the two transitions couple only to classical modes, and show some examples of the proton dynamics near the saddle point region. Finally we discuss, under what circumstances a concerted transfer of both particles may be more favorable than two subsequent transitions.