Electrochemical bond-breaking reactions: A comparison of large scale simulation results with analytical theory

The adiabatic free energy surface for the electrochemically induced dissociation of a methyl halide MeX (MeX + e(-) --> Me + X(-)) is computed from molecular dynamics (MD) simulations based on an underlying Hamiltonian developed to describe such processes. A two-dimensional free energy surface as a function of a collective solvent coordinate and the intramolecular Me-X bond length is computed. The theoretical basis of the simulations is a novel extension of the Anderson-Newns Hamiltonian to describe the coupling of the electron transfer to the bond-breaking process. A comparison of the simulation results is made with the standard analytical theory which is developed by virtue of several simplifying assumptions. It is found that the nonlinear microscopic features of the system produce significant deviations from the predictions of the analytical model.