Surface gliding of large low-dimensional clusters

Surface diffusion of a large cluster moving is a whole ("gliding") is analyzed in the framework of a kinetic theory combined with an explicit treatment of intracluster motion. A "dynamical" misfit caused by the thermal vibrations of the cluster's:atoms is shown to lead to a dramatic increase of the preexponential Factor in the diffusion coefficient, while size effects in the cluster-substrate-bath coupling enhance The occurrence of long jumps for larger clusters. The results constitute an explanation of recent ;puzzling observations for compact 2D clusters Ir-19 and Ir-7 on the Ir(111) surface.