Relaxation of hot atoms following H2 dissociation on a Pd(111) surface

N. PINEAU, H.F. BUSNENGO, J.C. RAYEZ Y A. SALIN

JOURNAL OF CHEMICAL PHYSICS

Año: 2005 vol. 122 p. 214705 - 214713

0021-9606

We study the relaxation of hot H atoms produced by dissociation of H2 molecules on the Pd(111) surface. Ab initio density-functional theory calculations and the “corrugation reducing procedure” are used to determine the interaction potential for a H atom in front of a rigid surface as well as its modification under surface-atom vibrations. A slab of 80 Pd atoms is used to model the surface together with “generalized Langevin oscillators” to account for energy dissipation to the bulk. We show that the energy relaxation is fast, about 75% of the available energy being lost by the hot atoms after 0.5 ps. As a consequence, the hot atoms do not travel more than a few angstroms along the surface before being trapped into the potential well located over the hollow site.