Melting temperature of tungsten from twoab initioapproaches

Abstract

We have calculated the melting temperature of tungsten by two ab initio approaches. The first approach can be divided into two steps. In the first step, we simulate a large coexisting solid and liquid system by the classical embedded-atom method potential and obtain an approximate melting temperature. In the second step, we compute the accurate melting temperature by performing the ab initio free-energy corrections. The second approach is to perform a direct ab initio molecular-dynamics simulation for the coexisting solid and liquid system using the constant particle number, pressure, and enthalpy ensemble. In the second approach, the simulation is carried out entirely using a density-functional theory Hamiltonian, and no other approximations are imposed. However, the simulation is performed using a relatively small supercell. The results obtained from two ab initio approaches can provide a check for each other. Our results show that they are in good agreement with each other and also in reasonably good agreement with the experimental value.