FIRST-PRINCIPLES STUDY OF THE EFFECTS OF GOLD ADSORPTION ON THE Al(001) SURFACE PROPERTIES

In this paper, we have studied theoretically the effects of gold adsorption on the Al(001) surface, using ab initio pseudo-potential method in the framework of the density functional theory. Having found the hollow sites at the Al(001) surface as the most preferred adsorption sites, we have investigated the effects of the Au adsorption with different coverages (Theta = 0.11, 0.25, 0.50, 0.75, 1.00 ML) on the geometry, adsorption energy, surface dipole moment, and the work function of the Al(001) surface. The results show that even though the work function of the Al substrate increases with the Au coverage, the surface dipole moment decreases with the changes in coverage from Theta = 0.11 to 0.25 ML. We have explained this behavior by analyzing the electronic and ionic charge distributions. Furthermore, by studying the diffusion of Au atoms into the substrate, we have shown that at room temperature the diffusion rate of Au atoms into the substrate is negligible but increasing the temperature to about 200 degrees C the Au atoms significantly diffuse into the substrate, in agreement with the experiment.