Surface segregation and relaxation calculated by the embedded-atom method: Application to face-related segregation on platinum-nickel alloys

The embedded-atom method (EAM) [M.S. Daw and M. I. Baskes, Phys. Rev. Lett. 50, 1285 (1983); Phys. Rev. B 29, 6443 (1984)] is applied to surface segregation and surface relaxation of binary alloys. This method needs no ad hoc size-mismatch strain energy and can handle arbitrary interlayer distances at the surface. Three low-index faces of platinum-nickel alloys are studied. Previously, low-energy electron diffraction investigations have established a face-related segregation on platinum-nickel alloys, with platinum enrichment on the (111) surface and nickel enrichment on the (110) surface. This work shows that EAM is capable of reproducing the experimentally determined segregation and relaxation with a good accuracy. In addition, EAM predicts the existence of a metastable concentration profile on the ${\mathrm{Pt}}_{0.5}$ ${\mathrm{Ni}}_{0.5}$(110) surface.