Diffusion mechanisms on Ni surfaces

Abstract

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. Cohen, J.B. Adams and A.F. Voter, Surf. Sci. 253 (1991) 334 [1]). This paper presents calculations of the formation and migration energies of vacancies in Ni surfaces, including (100), (110), (111), (311), and (331). In all cases, the activation energies for vacancy diffusion are higher than those for single adatoms. Formation energies of ledges and kinks on (100), (110), and (111) Ni surfaces were calculated. The interactions of single adatoms with ledges and kinks and diffusion of single adatoms on the stepped Ni surfaces were determined. Finally, MD simulations of surface diffusion of a single adatom on a Ni(111) surface were carried out to confirm the earlier molecular statics calculations and to test a simple Debye model.