The diffusion of 2-dimensional adatom islands on face-centered cubic (100) metal surfaces was been studied via large-scale Monte Carlo simulations of a lattice-gas model, with energetics that were based upon effective medium theory calculations. It was shown that, in the limit of large islands, the diffusive motion changed from a periphery-dominated mechanism to a regime where vacancies diffused within the island. Various atomistic processes for the diffusion of islands of differing sizes were considered. This analysis revealed the nature of the cross-over behavior in terms of the underlying microscopic processes. Memory effects were also studied by examining the temporal behavior of the velocity autocorrelation function. It was found that there were no anomalies in the long-term correlations of the microscopic processes.

Time Correlations and Statistics of Atomistic Processes in Island Diffusion on FCC (100) Metal Surfaces. J.Heinonen, I.T.Koponen, P.Salo, T.Ala-Nissila: Surface Science, 2002, 507-510, 146-9