Field-ion microscopy measurements revealed a large value of the diffusion pre-factor for the Pt7 cluster; exceeding those of small Ptn(n ≤ 4) clusters by two orders of magnitude. Here, using long-term (about 0.2µs) simulations and the tracing of interstitial atoms on the surface, a linear relationship was obtained between the mean square displacement of the cluster mass-center and the simulation time. The activation energy and pre-factor for two-dimensional atomic clusters Ptn(1 ≤ n ≤ 7) on the Pt(111) surface were determined by molecular dynamics. The present simulations could interpret the experimental data reasonably well. The large pre-factor of the Pt7 cluster could be attributed to a large number of non-equivalent diffusion processes having similar activation energies on the soft Pt surface.

Dynamical Simulations of Ptn(1≤n≤7) Clusters on Pt(111) Surface. Tang, J., Yang, J.: Physica B, 2011, 406[13], 2543-7