Nonadiabatic Dynamics of Molecules Interacting with Metal Surfaces: A Quantum-Classical Approach Based on Langevin Dynamics and the Hierarchical Equations of Motion

TL;DR

This paper introduces a new mixed quantum-classical method combining hierarchical equations of motion and Langevin dynamics to accurately simulate nonadiabatic molecular dynamics at metal surfaces, capturing strong interactions.

Contribution

It extends existing methods by integrating nonperturbative, non-Markovian treatment of molecule-metal interactions with quantum and classical dynamics.

Findings

Successfully applied to molecular nanojunctions with strong interactions.

Accurately captures nonadiabatic effects and electron-electron interactions.

Provides a versatile framework for simulating complex surface-molecule systems.

Abstract

A novel mixed quantum-classical approach to simulating nonadiabatic dynamics of molecules at metal surfaces is presented. The method combines the numerically exact hierarchical equations of motion approach for the quantum electronic degrees of freedom with Langevin dynamics for the classical degrees of freedom, namely, low-frequency vibrational modes within the molecule. The approach extends previous mixed quantum-classical methods based on Langevin equations to models containing strong electron-electron or quantum electronic-vibrational interactions, while maintaining a nonperturbative and non-Markovian treatment of the molecule-metal coupling. To demonstrate the approach, nonequilibrium transport observables are calculated for a molecular nanojunction containing strong interactions.