Modeling solid-liquid interfaces using next generation quantum molecular dynamics

Abstract

We demonstrate the applicability of extended Lagrangian Born-Oppenheimer quantumbased molecular dynamics (XL-BOMD) to model electron transfer reactions occurring on solidliquid interfaces. Specifically, we consider the reduction of O 2 as catalyzed at the interface of an N-doped graphene sheet and H 2 O at fuel cell cathodes. This system is a good testbed for nextgeneration computational chemistry methods since the electrochemical functionalities strongly depend on atomic-scale quantum mechanics. As opposed to prior iterations of first principles molecular dynamics, XL-BOMD only requires a full self-consistent-charge relaxation during the initial time step. The electronic ground state and total energy are stabilized thereafter through nuclear and electronic equations of motion assisted by an inner-product kernel updated with low-rank approximations. A species charge analysis reveals that the kernel-based XL-BOMD simulation can capture an electron transfer between the PGM-free catalyst and a solvated O 2 molecule mediated by H 2 O, which results in the molecular dissociation of O 2 .