Quasiharmonic versus exact surface free energies of Al: A systematic study employing a classical interatomic potential

We discuss a computationally efficient classical many-body potential designed to model the Al-Al interaction in a wide range of bonding geometries. We show that the potential yields results in excellent agreement with experiment and ab initio calculations for a number of bulk and surface properties, among others for surface and step formation energies, and self-diffusion barriers. As an application, free-energy calculations are performed for the Al (100) surface by Monte Carlo thermodynamic integration and the quasiharmonic approximation. Comparison of the latter approximation with the reference Monte Carlo results provides information on its range of applicability to surface problems at high temperatures. [S0163-1829(99)03831-X].