Molecular dynamics simulation of liquid–vapor phase diagrams of metals modeled using modified empirical pair potentials

Abstract

We propose a modified form of pair potential for metals. The parameters of the potential are obtained by fitting the cold curve of the potential to that obtained from the ab-initio calculations. Parameters have been obtained for aluminum, copper, sodium and potassium. To test the accuracy of the potentials, we performed particle-transfer molecular dynamics simulations and obtained the liquid–vapor coexistence curves of the above metals. We found that, in the cases of sodium and potassium, the present results improve significantly over those obtained from Morse potential. In the cases of aluminum and copper, the present results are closer to those obtained from the Morse potential. We also obtained isobars of aluminum and copper at 0.3GPa from NPT ensemble simulations. We observed that the isobars obtained using the Morse potential and the modified potentials are in close agreement in both the cases. The obtained isobar of copper is in reasonable agreement with the experimental isobar while that of aluminum is slightly deviating from the experimental isobar.