Ab initio study of cesium chemisorption on the GaAs(110) surface.

Abstract

Different possible adsorption sites of cesium atoms on a gallium arsenide (110) surface have been investigated using ab initio self-consistent unrestricted Hartree-Fock total-energy cluster calculations with Hay-Wadt effective-core potentials. The effects of electron correlation have been included by invoking the concepts of many-body perturbation theory and are found to be highly significant. We find that the Cs atom adsorption at a site modeled with a ${\mathrm{CsGa}}_{5}$${\mathrm{As}}_{4}$${\mathrm{H}}_{12}$ cluster is most favored energetically followed by Cs adsorption at a site modeled with the ${\mathrm{CsGa}}_{4}$${\mathrm{As}}_{5}$${\mathrm{H}}_{12}$ cluster. For molecular cesium, a site modeled by a ${\mathrm{Cs}}_{2}$${\mathrm{Ga}}_{6}$${\mathrm{As}}_{9}$${\mathrm{H}}_{21}$ cluster is most favored energetically. However, here all four sites considered remain competitive energetically at the correlated levels of theory. The effects of charge transfer from Cs and ${\mathrm{Cs}}_{2}$ to the GaAs surface and the possibilities of metallization are also analyzed and discussed.