MODELING OF SURFACE RELAXATION AND MELTING OF ALUMINUM

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) su rfaces of fee 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 profil es and radial distribution functions. The many-body potential overesti mates the bulk melting temperature (T-m approximate to 1275+/-25 K) by approximately 37% but reproduces the sharp melting transition observe d experimentally. To obtain a melting point in agreement with experime nt we would need to lower the energy scaling parameter (determined fro m 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 . (C) 1997 Elsevier Science BV.