Molecular Dynamic Simulation of Liquid-Vapor Coexistence of Metals Modeled Using Modified Empirical Pair Potentials

TL;DR

This study develops a modified empirical pair potential for metals, fitted to ab-initio data, and uses molecular dynamics to accurately simulate liquid-vapor coexistence and isobars for Aluminum, Copper, Sodium, and Potassium.

Contribution

The paper introduces a new modified pair potential for metals, improving simulation accuracy for Sodium and Potassium compared to previous models.

Findings

Improved liquid-vapor coexistence curves for Sodium and Potassium.

Close agreement of isobars with experimental data for Copper.

Slight deviation of Aluminum isobar from experimental results.

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 (J.K. Singh et. al., Fluid Phase Equilibria 248(2006)). 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.