First principles studies of elastic and thermodynamic properties of fcc-VH2 with pressure and temperature

Abstract In this work, we study elastic and thermodynamic properties of VH 2 at different pressures and temperatures. Elastic constants and bulk modulus of VH 2 decrease with increase in temperature, and hence increase with pressure. Thermal expansion of the crystal lattice will be suppressed by high pressure. When the temperature is 1500 K, 15.99 GPa of pressure can completely restrain the volume expansion caused by temperature. At a given pressure, the lower the temperature, the easier the cell compression. At low temperatures, C v is proportional to T 3 , and C v tends to the Dulong–Petit limit at higher temperatures. The Debye temperature increases with pressure, but decreases with temperature. At low temperature and low pressure, thermal expansion coefficient increases sharply with temperature. At high temperature and high pressure, the increasing trend slows down.