  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 properties in excellent agreement with
experiment and ab initio results 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 quasi-harmonic
approximation. Comparison of the latter approximation with the reference Monte
Carlo results provides informations on its range of applicability to surface
problems at high temperatures.
