First-principles prediction of the equation of state for TcC with rocksalt structure

The predicted P-V-T equations of state for TcC in the rocksalt structure using first-principles density functional theory calculations combined with the quasi-harmonic Debye model in which the phononic effects are considered. It can be found that the volume is greatly affected by both pressure and temperature, and the effect of increasing pressure on rocksalt TcC is the same as decreasing temperature of rocksalt TcC. At a given temperature, the volume decreases with the increase in pressure, and the volume at lower temperature is less than that at higher temperature for a given pressure. On the other hand, at higher temperatures and under lower pressures, the volume of rocksalt TcC is greatly affected by the pressure compared with the lower temperatures and under lower pressures.