Calculations were made of the facet/facet barriers for the atomic diffusion of small Cu clusters (up to 8 atoms) from {111} facets to {111} or {100} facets. In each case, attention was concentrated on the atom-by-atom diffusion process. This was because that mechanism had previously been found to be the most energetically favourable. The results showed that, for all of the clusters considered, the diffusion barriers became independent of the facet size for 3 or more atomic layers. In addition, clusters bigger than trimers presented similar lowest facet/facet barriers; except for heptamers, which exhibited the highest activation energy. In general, for single steps, diffusion from {111} to {111} required smaller, lowest and highest energy barriers, than did diffusion from {111} to {100}. For multiple steps (facets), both cases exhibited similar behaviours. It was noted that all of these barriers were significantly greater than for the corresponding concerted cluster diffusion over a plane.

Atom Diffusion of Small Cu Clusters across Facet–Facet Barriers over Cu{111} Surfaces. B.H.Aguilar, J.C.Flores, A.M.Coronado, H.Huang: Modelling and Simulation in Materials Science and Engineering, 2007, 15[5], 419-26