Non-Adiabatic Vibrational Damping of Molecular Adsorbates: Insights into Electronic Friction and the Role of Electronic Coherence

TL;DR

This paper introduces a perturbation method based on time-dependent density-functional theory to analyze non-adiabatic vibrational damping of adsorbates, revealing the significant impact of electronic coherence times on electronic friction and vibrational lifetimes.

Contribution

It provides a novel computational approach to quantify electron-hole pair excitations and highlights the importance of electronic coherence times in vibrational damping on metal surfaces.

Findings

Short electronic coherence times diminish band structure effects.

Electronic coherence influences vibrational lifetimes and chemicurrent signals.

The method offers insights into non-adiabatic vibrational energy dissipation.

Abstract

We present a perturbation approach rooted in time-dependent density-functional theory to calculate electron hole (eh)-pair excitation spectra during the non-adiabatic vibrational damping of adsorbates on metal surfaces. Our analysis for the benchmark systems CO on Cu(100) and Pt(111) elucidates the surprisingly strong influence of rather short electronic coherence times. We demonstrate how in the limit of short electronic coherence times, as implicitly assumed in prevalent quantum nuclear theories for the vibrational lifetimes as well as electronic friction, band structure effects are washed out. Our results suggest that more accurate lifetime or chemicurrent-like experimental measurements could characterize the electronic coherence.