Molecular dynamics simulations of the diffusion and rotation of Pt nanoclusters supported on graphite

We study the diffusion and rotation of Pt nanoclusters supported on graphite. Using molecular dynamics simulation, we reveal that the supported Pt clusters have two types of bottom layers: a hexagonal lattice and a rectangular lattice. The diffusion rate of the Pt clusters mainly depends on the types of bottom layers. This observation is explained by the periodic lattice matching between the bottom layer and the graphite. In addition to lateral diffusion, we find that the Pt clusters with a rectangular or mixed lattice tend to rotate or wag on the z axis. By using the rotation rates and total movements of all atoms, we show that the rotation of a Pt cluster can be induced by the difference in the diffusion rates for the different types of bottom layers. This outcome is well in accord with our diffusion mechanism.