Simulations were used to follow the dynamics of the motion of hexagonal Pt heptamers on Pt(111). Close-packed Pt7 clusters on face-centered cubic sites were found to be very stable structures with reconfiguration or translation events occurring only rarely over simulation times above 30ns at 1000K. The adsorption of a single adatom on the cluster surface, however, induced rapid intracluster bond breaking, reconfiguration, the introduction of stacking faults, and greatly enhanced cluster diffusion rates. Cluster migration occurred primarily via sequences of individual atom and concerted dimer jumps, but concerted cluster motion was also observed. The adatoms eventually descended to the terrace, predominantly by push-out/exchange reactions with cluster atoms at B edges.

Adatom-Induced Diffusion of Two-Dimensional Close-Packed Pt7 Clusters on Pt(111). Münger, E.P., Chirita, V., Greene, J.E., Sundgren, J.E.: Surface Science, 1996, 355[1-3], L325-30