Vacancy formation enthalpy at high pressures in tantalum

Using a mixed basis pseudopotential method, total energy calculations were performed to obtain the enthalpy of vacancy formation in Ta as a function of pressure, which is important for understanding the effects of pressure on mechanical properties. The vacancy formation enthalpy is found to increase from 2.95 eV at ambient pressures to 12.86 eV at 300 GPa, and the vacancy formation volume decreases from being 53 +/- 5% of the bulk volume per atom at ambient pressure to 20 +/- 2% at 300 GPa, for a 54-atom supercell. We also show that there is a strong correspondence between the vacancy formation enthalpy and the melting temperature in Ta.