Comparison of the stability of small clusters of hydrogen near a Pd(001) or a Ni(001) surface

Abstract

Experimental data show that the H/Pd(001) system presents an ordered phase while a more diffuse diagram is observed for H/Ni(001). Using Green-function properties, we developed recently a formalism to describe the electronic structure of finite size hydrogen clusters near a metallic surface. Any atomic configuration can be considered in this real-space tight-binding framework. Multi-atom interactions are obtained as global quantities, getting round the explicit computation of differences between large numbers. Using this formalism, we present a comparison of the stability of small clusters of hydrogen near a Pd and a Ni surface. The stages of the growth in the case of H in Pd are described, and very good agreement with experimental results is obtained. In the case of H in Ni, the multi-atom interaction energies are very small, as observed experimentally.