Electronic damping of molecular motion at metal surfaces

TL;DR

This paper introduces a TDDFT-based method to calculate electron-hole pair excitation damping rates for atomic and molecular motion at metal surfaces, removing periodicity artifacts and enabling isolated system analysis.

Contribution

It develops a parallelized TDDFT approach within the CASTEP framework to accurately compute damping rates for molecules on metal surfaces, addressing periodicity issues.

Findings

Demonstrated damping calculations for hydrogen on Cu(111) surface.

Implemented a super-cell removal technique for isolated system results.

Validated the method with test results on hydrogen atom damping.

Abstract

A method for the calculation of the damping rate due to electron-hole pair excitation for atomic and molecular motion at metal surfaces is presented. The theoretical basis is provided by Time Dependent Density Functional Theory (TDDFT) in the quasi-static limit and calculations are performed within a standard plane-wave, pseudopotential framework. The artificial periodicity introduced by using a super-cell geometry is removed to derive results for the motion of an isolated atom or molecule, rather than for the coherent motion of an ordered over-layer. The algorithm is implemented in parallel, distributed across both ${\bf k}$ and ${\bf g}$ space, and in a form compatible with the CASTEP code. Test results for the damping of the motion of hydrogen atoms above the Cu(111) surface are presented.