Field-ion microscopy, and molecular statics methods which involved embedded-atom potentials, were used to identify surface diffusion modes for Pt dimers and trimers on the (001) surface. It was found that the dimers migrated via a series of displacements which involved exchanges between one of the dimer atoms and a substrate atom. They had a lower activation barrier for diffusion than did monomers. The diffusion of trimers involved both exchange and hopping displacements, and the activation barrier was comparable to that for monomers.

G.L.Kellogg, A.F.Voter: Physical Review Letters, 1991, 67[5], 622-5