Modelling of surface relaxation and melting of aluminium

Abstract

An empirical potential energy function, comprising two- and three-body terms, has been derived for aluminium. This potential reproduces the experimental energies and relaxations of the (111), (110) and (100) surfaces of fcc Al to a high degree of accuracy. The melting of bulk fcc Al and its low index surfaces has been studied in detail by employing Monte Carlo simulation techniques. Melting has been defined in terms of a number of calculated quantities: order parameters, density profiles and radial distribution functions. The many-body potential overestimates the bulk melting temperature ( T m ≈ 1275 ± 25 K) by approximately 37% but reproduces the sharp melting transition observed experimentally. To obtain a melting point in agreement with experiment we would need to lower the energy scaling parameter (determined from room temperature data) by 37%. The potential also indicates that the relatively open (110) surface melts about 200 K below the bulk, while the denser (100) surface does not melt until T m. These findings are again in good agreement with experiment and with previous calculations.