Nucleation and mobility model of Agn clusters adsorbed on perfect and oxygen vacancy MgO surfaces.

The structures and energy properties for Ag(n) (n = 1-8) metal clusters adsorbed on the perfect and oxygen vacancy MgO surfaces have been studied by using the DFT/UB3LYP method with an embedded cluster model. The nucleation and mobility model for the Ag(n) (n = 1-8) clusters on the perfect and oxygen vacancy MgO(100) surfaces was investigated. The results show that the Ag atoms locate initially at the surface oxygen vacancy sites; then, with the growth of Ag cluster sizes, the large Ag clusters move possibly out of the vacancy sites by a rolling model, and diffuse on the MgO surface under a certain temperature condition. The relative energies needed for moving out of the oxygen vacancy region for the adsorbed Ag(n) clusters with the rolling model have been predicted. The even-odd oscillation behaviors for the cohesive energies, nucleation energies, first ionization potentials and HOMO-LUMO gaps of the adsorbed Ag(n) clusters with the variation of cluster sizes have also been discussed.