SURFACE EFFECTS ON PT-NI SINGLE-CRYSTALS CALCULATED WITH THE EMBEDDED-ATOM METHOD

Recent scanning-tunneling-microscopy (STM) experiments on Pt25Ni75(111 ) and Pt10Ni90(110) surfaces showing lattice mismatch dislocations nea r the surface and surface ordering phenomena have been verified in sim ulation calculations using the embedded-atom method (EAM). It was foun d that the EAM can be successfully applied for the calculation of orde ring effects and crystal defects such as dislocations using energy min imization routines and Monte Carlo calculations. By comparing experime ntal data and EAM results, it was possible to determine the depth on t he dislocations and therefore the number of layers with Pt enrichment on the surface. For the (111) face exhibiting surface ordering phenome na, the calculated short-range order is in agreement with STM data whe re the two species could be clearly distinguished.