Surface segregation in CuPt alloys by means of an improved modified embedded atom method

We present a procedure to investigate surface structures in CuPt alloys by combining the modified embedded atom method (MEAM) and the cluster expansion method (CEM). While the MEAM provides structural information for the description of extended anisotropic defects, the CEM improves the ability to correctly reproduce the relevant ground state structures in agreement with ab initio data. The procedure is validated with the reproduction of surface energies of pure Cu and Pt, the prediction of TC for order-disorder transitions, the surface and segregation energies in ordered CuPt alloys, and Monte Carlo (MC) simulations of temperature-dependent surface segregation profiles. A complete MEAM-CEM/MC study of the surface segregation in Cu3Pt, CuPt, and CuPt3 alloys is presented, engaging only 11 composition- and volume-independent alloy-specific parameters. Results are critically compared with experimental data from literature and with an independent set of ab initio periodic density functional theory calculations.