Simulation of the electron transfer process Cu2++Cu+reversible arrow Cu++Cu2+ in aqueous solution

A Monte Carlo simulation is performed to investigate the role of solvent in the Cu2+/Cu+ electron exchange process in water. This study is based on the classical Marcus model using the energy gap between the reactant and product states as the reaction coordinate. Since the process has a rather high activation free energy, conventional simulations are not best suited to its complete description, and thus special sampling techniques are required. In this case, a mapping potential is used to drive the system from the reactants to the transition state, and free energies are computed by thermodynamic perturbation and thermodynamic integration methods. A comparison is made between the results obtained by both methods and conclusions are drawn concerning the applicability of the Marcus model to this kind of process.