Quasi-Diabatic Propagation Scheme for Direct Simulation of Proton-Coupled Electron Transfer Reaction

We apply a recently developed quasi-diabatic (QD) propagation scheme to simulate proton-coupled electron transfer (PCET) reactions. This scheme enables a direct interface between an accurate diabatic dynamics approach and the adiabatic vibronic states of the coupled electron–proton subsystem. It explicitly avoids theoretical efforts to preconstruct diabatic states for the transferring electron and proton or reformulate a diabatic dynamics method to the adiabatic representation, both of which are nontrivial tasks. Using a partial linearized path-integral approach and symmetrical quasi-classical approach as the diabatic dynamics methods, we demonstrate that the QD propagation scheme provides accurate vibronic dynamics of PCET reactions and reliably predicts the correct reaction mechanism without any a priori assumptions. This work demonstrates the possibility to directly simulate challenging PCET reactions by using accurate diabatic dynamics approaches and adiabatic vibronic information.