The self-diffusion behaviors of two-dimensional compact hexagonal Cu7 and Pt7 clusters on the (111) surface were studied via molecular dynamics simulation. The diffusion barriers and pre-factors were determined from the Arrhenius diagram and compared with recent low-temperature field-ion microscopy experiments. It was found that the D0 of Pt7 clusters was about 35 times larger than that of Cu7 clusters. From the calculated phonon spectral densities of adatoms, it was suggested that the differing diffusion behaviors of the two clusters could result from strong interactions between the Pt adatoms and surface atoms, which made the non-equivalent self-diffusion processes, which could produce a high pre-factor, occurred more easily for Pt7 clusters.

Comparative Study of Compact Hexagonal Cluster Self-Diffusion on Cu(111) and Pt(111). J.Yang, W.Hu, M.Xu: Applied Surface Science, 2008, 255[5], 1736-40