Molecular dynamics simulations were used to monitor the dynamics of small 2-dimensional Pt clusters on Pt(111) surfaces at 1000K. It was noted that, whereas close-packed Pt7 heptamers were extremely stable structures, the addition of a single cluster vacancy, or an on-top adatom, immediately resulted in intra-cluster bond-breaking, reconfiguration, rotation and the introduction of stacking faults. The cluster diffusion rate was also greatly enhanced. The mapping of center-of-mass motions, for simulation times of more than 145ns, revealed increases in cluster velocities of more than an order of magnitude. Cluster migration occurred mainly via concerted motion and a novel diffusion mechanism which involved the double-shearing of dimers and trimers. It was concluded, contrary to previous reports, that edge-atom diffusion played only a minor role.

Enhanced Cluster Mobilities on Pt (111) during Film Growth from the Vapor Phase V.Chirita, E.P.Münger, J.E.Sundgren, J.E.Greene: Applied Physics Letters, 1998, 72[1], 127-9