Energy loss of atoms at metal surfaces due to electron-hole pair excitations: First-principles theory of "chemicurrents"

TL;DR

This paper introduces a first-principles method to calculate energy loss from atoms at metal surfaces due to electron-hole pair excitations, providing theoretical estimates of chemicurrents observed experimentally.

Contribution

It presents an ab initio approach to model energy dissipation and electron-hole pair excitation for atoms interacting with metal surfaces, linking theory with experimental chemicurrent measurements.

Findings

The method accurately estimates chemicurrents for H and D atoms on Cu(111).

The approach provides a position-dependent friction coefficient from pseudopotential calculations.

The semi-classical model successfully describes electron excitation due to incident atoms.

Abstract

A method is presented for calculating electron-hole pair excitation due to an incident atom or molecule interacting with a metal surface. Energy loss is described using an \textit{ab initio} approach that obtains a position-dependent friction coefficient for an adsorbate moving near a metal surface from a total energy pseudopotential calculation. A semi-classical forced oscillator model is constructed, using the same friction coefficient description of the energy loss, to describe excitation of the electron gas due to the incident molecule. This approach is applied to H and D atoms incident on a Cu(111) surface, and we obtain theoretical estimates of the `chemicurrents' measured by Nienhaus et al [Phys. Rev. Lett. \textbf{82}, 446 (1999)] for these atoms incident on the surface of a Schottky diode.