Adatom-induced diffusion of two-dimensional close-packed Pt-7 clusters on Pt(111)

Molecular dynamics simulations were used to follow the dynamics of the motion of hexagonal Pt heptamers on Pt(111). Close packed Pt-7 clusters on fee sites were found to be very stable structures with reconfiguration or translation events occurring only rarely over simulation times >30 ns at 1000 K. 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 through sequences of individual atom and concerted dimer jumps, but concerted cluster motion was also observed. The adatoms eventually descended to the terrace, predominantly through push-out/exchange reactions with cluster atoms at B edges.