DIFFUSION MECHANISMS ON NI SURFACES

The embedded atom method (EAM) was previously used to study diffusion of single Ni adatoms on various Ni surfaces; the calculated diffusion rates were in excellent agreement with experiment (C.L. Liu, J.M. Cohe n, J.B. Adams and A.F. Voter, Surf. Sci. 253 (1991) 334 [1]). This pap er presents calculations of the formation and migration energies of va cancies in Ni surfaces, including (100), (110), (111), (311), and (331 ). In all cases, the activation energies for vacancy diffusion are hig her than those for single adatoms. Formation energies of ledges and ki nks on (100), (110), and (111) Ni surfaces were calculated. The intera ctions of single adatoms with ledges and kinks and diffusion of single adatoms on the stepped Ni surfaces were determined. Finally, MD simul ations of surface diffusion of a single adatom on a Ni(111) surface we re carried out to confirm the earlier molecular statics calculations a nd to test a simple Debye model.