Electronic structure of heteroepitaxial metallic islands: a Hartree-Fock study at semiempirical level

Hartree-Fock calculations at semiempirical level have been used to describe the electronic configuration of metallic islands epitaxially grown on a metallic substrate (the elements used for the island and the substrate are Ag, Cu and Ag, Cu and Fe, respectively). The functional dependence of the island energy on composition, shape and lattice mismatch with the substrate is analyzed. A similar analysis is also carried out for the energy barriers for adatom diffusion. The results indicate a central role of the electronic charge. In fact, the evolution of the island structure towards a three dimensional or layered shape is determined by the properties of the electronic charge. Also the properties of the adatoms energies, i.e. change along the island height and dependence on the structure and composition of the epitaxial system, are explained as electronic effects.