Formation and dynamics of hot-precursor hydrogen atoms on metal surfaces: Trajectory simulations and stochastic models

摘要

The results of a theoretical study of H atoms colliding with a Cu(lll) surface are presented. The metal is treated as a five-layer slab of 150 atoms, and all dynamics are classical. The formation of trapped ''hot-precursor'' atoms on the surface is examined, as well as the nature of their motion on the surface and their energy and momentum dissipation. Connections are made with recent Eley-Rideal experiments, for which hot-atom precursors may play an important role. To facilitate future simulations of Eley-Rideal and hot-atom reactions on metals, simple stochastic models are developed to describe hot-atom energy dissipation. A Fokker-Planck equation is used to model the hot-atom energy distribution. Quasi-Langevin terms, which simulate fluctuation and dissipation consistent with this Fokker-Planck description, are developed for the hat-atom equations of motion. These quasi-langevin terms are different from the hydrodynamic forms used for Brownian-type motion. (C) 1998 American Institute of Physics. [References: 52]