# Temperature-Dependent Lifetimes of Low-Frequency Adsorbate Modes from Non-Equilibrium Molecular Dynamics Simulations

## TL;DR

This study uses non-equilibrium molecular dynamics to calculate temperature-dependent vibrational lifetimes of low-frequency adsorbate modes on metal surfaces, revealing new insights into damping mechanisms.

## Contribution

First to extract vibrational lifetimes from non-equilibrium MD simulations considering both phononic and electronic damping channels.

## Key findings

- Damping mechanisms are additive, contrary to textbook predictions.
- A simple harmonic-anharmonic model semi-quantitatively matches temperature dependence.
- Electronic and phononic contributions to damping are quantitatively separated.

## Abstract

We present calculations on the damping of a low-frequency adsorbate mode on a metal surface, namely the frustrated translation of Na on Cu(100). For the first time, vibrational lifetimes of excited adlayers are extracted from non-equilibrium molecular dynamics calculations accounting for both the phononic and the electronic dissipation channels. The relative contributions of the two damping mechanisms, which we show to be additive, are found to disagree with textbook predictions. A simple model based on separable harmonic and anharmonic contributions is able to semi-quantitatively reproduce the temperature dependence of the computed lifetimes.