First-principles investigations on the thermodynamic properties of YNi2B2C under high pressure

The thermodynamic properties of YNi2B2C under high pressures are studied by using the first-principles calculations based on the density-functional perturbation theory within the quasi-harmonic approximation. Both the isothermal bulk modulus B and the relative volume V/V0 have opposite change trends with increasing pressure, which is resulted from that the dramatic decrease in volume leads to the rapid increase in the isothermal bulk modulus. Furthermore, the variations of the volume expansion coefficients, the thermal expansion coefficients and the heat capacity with temperature and pressure are systematically studied in the ranges of 0-1200 K and 0-80 GPa.