Quantum corrected Langevin dynamics for adsorbates on metal surfaces interacting with hot electrons

TL;DR

This paper emphasizes the importance of using quantized initial conditions in Langevin dynamics to accurately model adsorbates interacting with hot electrons on metal surfaces, showing significant effects on desorption probabilities and vibrational state distributions.

Contribution

It introduces a method to incorporate quantum initial conditions into Langevin dynamics, improving accuracy over classical approaches for systems with quantum effects.

Findings

Quantized initial conditions significantly affect desorption probabilities.

Correct quantum initial conditions align Langevin dynamics with quantum master equations.

Application to CO on Cu(100) demonstrates large impact on vibrational state distributions.

Abstract

We investigate the importance of including quantized initial conditions in Langevin dynamics for adsorbates interacting with a thermal reservoir of electrons. For quadratic potentials the time evolution is exactly described by a classical Langevin equation and it is shown how to rigorously obtain quantum mechanical probabilities from the classical phase space distributions resulting from the dynamics. At short time scales, classical and quasiclassical initial conditions lead to wrong results and only correctly quantized initial conditions give a close agreement with an inherently quantum mechanical master equation approach. With CO on Cu(100) as an example, we demonstrate the effect for a system with ab initio frictional tensor and potential energy surfaces and show that quantizing the initial conditions can have a large impact on both the desorption probability and the distribution of molecular vibrational states.