Toward Detection of Electron-Hole Pair Excitation in H-atom Collisions with Au(111): Adiabatic Molecular Dynamics with a Semi-Empirical Full-Dimensional Potential Energy Surface

Abstract

We report an analytic potential energy surface (PES) based on several hundred DFT energies for
\nH interacting with a Au(111) surface. Effective medium theory is used to fit the DFT data, which
\nwere obtained for the Au atoms held at their equilibrium positions. This procedure also provides
\nan adequate treatment of the PES for displacements of Au atoms that occur during scattering of H
\natoms. The fitted PES is compared to DFT energies obtained from ab initio molecular dynamics
\ntrajectories. We present molecular dynamics simulations of energy and angle resolved scattering
\nprobabilities at five incidence angles at an incidence energy, Ei = 5 eV, and at a surface temperature,
\nTS = 10 K. Simple single bounce trajectories are important at all incidence conditions explored
\nhere. Double bounce events also make up a significant fraction of the scattering. A qualitative
\nanalysis of the double-bounce events reveals that most occur as collisions of an H-atom with two
\nneighboring surface gold atoms. The energy losses observed are consistent with a simple binary
\ncollision model, transferring typically less than 150meV to the solid per bounce.