Surface effects on Pt-Ni single crystals calculated with the embedded-atom method

Recent scanning-tunneling-microscopy (STM) experiments on ${\mathrm{Pt}}_{25}$${\mathrm{Ni}}_{75}$(111) and ${\mathrm{Pt}}_{10}$${\mathrm{Ni}}_{90}$(110) surfaces showing lattice mismatch dislocations near the surface and surface ordering phenomena have been verified in simulation calculations using the embedded-atom method (EAM). It was found that the EAM can be successfully applied for the calculation of ordering effects and crystal defects such as dislocations using energy minimization routines and Monte Carlo calculations. By comparing experimental data and EAM results, it was possible to determine the depth of the dislocations and therefore the number of layers with Pt enrichment on the surface. For the (111) face exhibiting surface ordering phenomena, the calculated short-range order is in agreement with STM data where the two species could be clearly distinguished.