MOLECULAR-DYNAMICS SIMULATION OF ADATOM DIFFUSION ON METAL-SURFACES

We propose, in this paper, a theoretical model to investigate surface self-diffusion of single adatoms on the face-centered-cubic metals. Ca lculations are performed on both close packed (111) and loosely packed (001) planes of rhodium and nickel. Two realistic model potentials ar e applied to describe the interatomic interaction of the adatom/substr ate systems. The first model is a Morse-type potential, which involves several empirical fitting of bulk properties of solid. The second new ly popular potential was introduced by Sutton and Chen, which incorpor ates with many-body effects. With these potentials, conventional molec ular dynamics (MD) is employed to obtain trajectories of the atoms. Th e averaged square displacements are computed for a range of initial ki netic energies, and the surface diffusion constants can be obtained by means of the Einstein relation. The estimated random walk exponential prefactors and activation energies exhibit Arrhenius behavior, which are confirmed with the previous results. Surface migration by an excha nge mechanism for self-diffusion on the Ni(001) plane is also discusse d.