Effects of surface structure and of embedded-atom pair functionals on adatom diffusion on fcc metallic surfaces

Abstract

Rates of self-diffusion on the (100) and (110) surfaces of nickel have been calculated using variational transition state theory (VTST) and four different interatomic potential energy functions based on the embedded-atom method (EAM). Static properties of a single nickel atom on the (111) surface, as well as on the (100) and (110) surfaces, are also presented. The embedded-atom pair functionals consist of effective pairwise additive and many-body cohesive interactions parameterized to the bulk and a few defect properties of nickel. VTST calculations of surface diffusion provide Arrhenius parameters and diffusion coefficients for comparison with experiment and among the four EAM potentials employed. An analysis of the estimated diffusion rates based on a hopping mechanism and the four pair functionals reveals that diffusion will occur more readily on the (111) surface and that self-diffusion on the (110) surface exhibits directional anisotropy. The diffusion rate variation from one pair functional to another is interpreted in terms of the effective pair potentials. © 1992.