First principles studies of overlayer-induced faceting

Using first principles total energy calculations, we studied the overlayer growth mode and the substrate stability when ultra-thin overlayers of various metals are grown on Mo(111) substrates. In close agreement with experimental results, we found that the growth modes are Stranski-Krastanov, and the overlayers of some metals can induce the substrate to facet. The faceting is basically driven by the enhancement of the surface energy anisotropy due to adsorption, and the interaction with the substrate are stronger for faceting agents than for non-faceting agents. In some cases it is energetically favorable for the substrate to transform to facets of more than one orientation, leading to the possible coexistence of two types of pyramidal facets.