By performing extensive density-functional calculations, using parallel computers, barriers were mapped out for self-diffusion at steps, kinks, and corners on (111) surfaces. The results revealed an unexpected exchange diffusion mechanism at kinks, and a large anisotropy at corners, and were used to predict various growth modes. The high accuracy and predictive power of the method was supported by a new scanning tunnelling microscopic study of Al on Al(111). This indicated that the present prediction of dendrites, rather than fractals, at low temperatures was confirmed by measurements made at 60 to 100K. A predicted transition to compact islands, at 118 to 122K, was in excellent agreement with an experimentally observed transition at 120K. The prediction of a transition to hexagonal islands, near to 200K, was experimentally confirmed by a transition at 200K. A predicted terrace diffusion barrier of 0.04eV was in good agreement with the experimental value of 0.042eV. Further Monte Carlo simulations were carried out, at 30 to 140K, for a wide range of deposition rates (10-6 to 1 monolayers/s). It was found that the transition to compact islands at 120K at a deposition rate of 0.0001 monolayers/s, and at about 130 to 140K at a deposition rate of 0.001 to 0.01 monolayers/s. The predictions agreed with experiment to within 10 to 20K.

Low-Symmetry Diffusion Barriers in Homo-epitaxial Growth of Al (111) A.Bogicevic, J.Strömquist, B.I.Lundqvist: Physical Review Letters, 1998, 81[3], 637-40