AN ABINITIO MO STUDY OF ALUMINUM ATOM ADSORPTION ON THE BASAL-PLANE OF GRAPHITE

Ab initio cluster calculation which model the adsorption of Al atoms on the basal plane of graphite are presented. One layer clusters find the Al prefers to adsorb at the center of the carbon rings. A two layer cluster determines the most stable Al adsorption site to be above the carbon atom in agreement with recent Scanning Tunneling Microscopy experiments. The charge distributions on the clusters are oscillatory and largely independent of the Al position. The form of the lowest unoccupied pi orbital for each cluster essentially determines the cluster charge distribution. From a constrained space orbital variation we find the on top site to be favored when Al and cluster wavefunctions are superimposed. However when the Al and pi orbitals interact the relaxation favors the open site. © 1990 IOP Publishing Ltd.