The melting temperature is the point at which a solid crystalline material melts. It determines the stability of a crystalline material’s lattice structure, and it is also used to assess the potential for chemical reactivity between the two phases (solid and liquid) of the system.
Lead has one of the lowest melting points of all metals at 621 F (327 C). The lower temperatures associated with this metal can cause component failure, so it is important to know its melting temperature before using it in high-temperature environments.
To accurately measure the melting temperature of a material, its Gibbs energies must be simulated in an ab initio calculation. Two approaches are available: The “coexistence approach” simulates the coexistence of a solid and liquid phase with classical interatomic potentials, and the “interface method” uses empirical potentials and ab initio calculations to determine the melting temperature of the sample.
The “coexistence approach” is a popular and efficient way to determine the melting temperature of a material, but it is highly dependent on the quality of the interatomic potentials that are used in the computation. These potentials must be transferable between the liquid and solid phases.
To capture the optimum potentials, three mechanisms must be monitored carefully in an ab initio calculation: ratio between solid and liquid phase, pressure-strain dependence, and void volume. Monitoring these quantities gives a strong basis to automatically discard unphysical data points such as full solid/liquid data points or interface structures with voids, and to ensure a high precision of the predicted melting temperature.