Molecular dynamics of disordered copper. A comparison of constant-pressure and constant-volume simulations

Abstract

We report the results of molecular dynamics calculations, at constant pressure and at constant volume, for copper in a disordered state. A comparison of the results of the simulations in the constant-pressure and constant-volume ensemble yields consistant thermodynamic and structural properties of the system. The dynamical properties of the ensembles are the same at short times, t<:0.2 ps, but there are slight differences at longer times. These arise from differences in the diffusion coefficients. The inclusion of a volume-dependent many-body term in the potential led to difficulties in the constant-pressure calculation. The possibility of using the constant-pressure molecular dynamics technique for the study of density changes in fusion-reactor materials after irradiation damage is discussed briefly.