A density functional study was made of the formation energies of (100)- and (111)-faceted steps on the (111) surface, as well as of the barrier to diffusion of an adatom on the flat surface. The step formation energies were found to have a ratio of 0.88 in favor of the (111)-faceted step; in excellent agreement with experiment. The equilibrium shape of islands was therefore expected to be non-hexagonal. The origin of the difference between the 2 steps was explained in terms of the release of stress at the surface, via relaxation. Relaxation was also found to be important with regard to the diffusion barrier, and led to a 20% decrease in its energy. The value which was deduced (0.33eV) was higher than that suggested by the available experimental data. The ratio of the step formation energies, and the diffusion barrier, were found to be the same whether the local-density approximation or the generalized-gradient approximation was used for the exchange and correlation energy.

Island Morphology and Adatom Self-Diffusion on Pt (111) G.Boisvert, L.J.Lewis, M.Scheffler: Physical Review B, 1998, 57[3], 1881-9