Interplay between electronic and phononic energy dissipation channels in the adsorption of CO on Cu(110)

TL;DR

This study uses advanced simulations to compare electronic and phononic energy dissipation during CO adsorption on Cu(110), revealing phonons dominate energy transfer, but electron-hole pairs accelerate energy dissipation near the surface.

Contribution

It introduces a full-dimensional neural network potential energy surface and compares models with and without electronic energy loss mechanisms in molecular adsorption.

Findings

Energy mainly transfers to lattice vibrations, determining adsorption probabilities.

Electronic friction has a minor role in energy transfer.

Electron-hole pair excitations accelerate energy dissipation near the surface.

Abstract

In this work, we investigate the relative importance of electronic and phononic energy dissipation during the molecular adsorption of CO on Cu(110). Initial sticking probabilities as a function of impact energy for CO impinging at normal incidence at a surface temperature of 90 K were computed using classical trajectory simulations. To this aim, we use a full-dimensional potential energy surface constructed using an atomistic neural network trained on density functional theory data obtained with the nonlocal vdW-DF2 exchange-correlation functional. Two models are compared: one allowing only energy transfer and dissipation from the molecule to lattice vibrations, and the other also incorporating the effect of molecular energy loss due to the excitation of electron-hole pairs, modeled within the local-density friction approximation. Our results reveal, firstly, that the molecule mainly transfers energy to lattice vibrations, and this channel determines the adsorption probabilities, with electronic friction playing a minor role. Secondly, once the molecule is trapped near the surface (where electronic density is higher), electron-hole pair excitations accelerate energy dissipation, significantly promoting CO thermalization. Still, the faster energy dissipation when electron-hole pair excitations are accounted for accelerates the accommodation of the adsorbed molecules in the chemisorption well but does not significantly alter their lateral displacements over the surface.