Quantum dynamics of model proton-coupled electron transfer reactions

We present detailed studies of the quantum dynamics of model proton-coupled electron transfer (PCET) reactions in solution. We compared the full quantum mechanical calculations with the mean field approaches for the solvent. A multiple time-scale wavepacket propagation method is used for simulating the combined electron/proton/solvent dynamics. The dynamics of the model PCET reactions are found to exhibit extensive mixing of the proton/electron adiabatic states. Such nonadiabatic couplings between adiabatic states are not properly described in mean field calculations except for at short times. The time-scale differences arising from the mass disparities of the different degrees of freedom can affect the detailed dynamics of the model PCET reactions, as illustrated by subtle differences in the sequential PT --> ET and ET --> PT mechanisms. (C) 2000 Elsevier Science B.V. All rights reserved.