Quantum Simulation of Heterogeneous Electron Transfer Free Energies at the Water-Metal Interface

摘要

The free energy for electron transfer is studied for the Fe(2+)/Fe(3+) chargetransfer system at the water-Pt(111) interface. Classical adiabatic free energy curves are calculated along with an adiabatic curve based on the Anderson-Newns Hamiltonian. Reactive flux calculations are then performed on this curve to determine the effect of recrossings on the classical rate constant. These effects are not found to be large (Kappa approx. 0.6) The solvent model is then extended to a quantum mechanical path integral version and quantum adiabatic free energy curves are calculated. The resulting quantum effects are found to be quite significant, illustrating that the same electrode overpotential does not necessarily result from the same free energy curves for the classical and quantum mechanical solvent models. These results suggest that classical models for water may not be adequate, or at least need to be modified, for accurate simulations of heterogeneous electron transfer. Chemical dynamics, Computer simulation, Electrochemistry.