Calculation of Melting Temperature Using Nonequilibrium Thermodynamic Integration Methods

Abstract

Melting temperature is a fundamental material property and is defined as the temperature at which the solid and liquid phases have the same free energy. However, there is no systematic study employing atomic simulations to calculate melting temperature using this definition. Here, molecular dynamics simulations and nonequilibrium thermodynamic integration methods are combined to calculate the melting temperature of Al and Cu. Results show that to accurately obtain the melting temperature, the model size should be considered carefully because the free energies of both solid and liquid phases are inversely proportional to the model size, causing a model size dependence on the calculated melting temperature. In addition, the melting temperature for various (semi-) empirical potential models for Al and Cu is calculated and verified against experimental values to provide guidelines for the choice of potential models for simulation-based problems relevant to the solid-liquid phase transformation. The melting temperatures of Al and Cu are calculated by combining molecular dynamics simulations and nonequilibrium thermodynamic integration methods. The calculated melting temperature is inversely proportional to the model size due to the strong dependence of free energy of the solid phase. The evaluation of melting temperature for various embedded-atom method potentials is also provided.image