AB-INITIO STUDY OF CESIUM CHEMISORPTION ON THE GAAS(110) SURFACE

Different possible adsorption sites of cesium atoms on a gallium arsen ide (110) surface have been investigated using ab initio self-consiste nt unrestricted Hartree-Fock total-energy cluster. calculations with H ay-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 at om adsorption at a site modeled with a CsGa5As4H12 cluster is most fav ored energetically followed by Cs adsorption at a site modeled with th e CsGa4As5H12 cluster. For molecular cesium, a site modeled by a Cs2Ga 6As9H21 cluster is most favored energetically. However, here all four sites considered remain competitive energetically at the correlated le vels of theory. The effects of charge transfer from Cs and Cs-2 to the GaAs surface and the possibilities of metallization are also analyzed and discussed.