First-principles investigations on elastic and thermodynamic properties of zinc-blende structure BeS

In this paper the elastic and thermodynamic proper-ties of the cubic zinc-blende structure BeS at different pressures and temperatures are investigated by using ab initio plane-wave pseudopotential density functional theory method within the generalized gradient approximation (GGA). The calculated results are in excellent agreement with the available experimental data and other theoretical results. It is found that the zinc-blende structure BeS should be unstable above 60GPa. The thermodynamic properties of the zinc-blende structure BeS are predicted by using the quasi-harmonic Debye model. The pressure-volume-temperature (P - V - T) relationship, the variations of the thermal expansion coefficient a and the heat capacity C-V with pressure P and temperature T, as well as the Gruneisen parameter-pressure-temperature (gamma - P - T) relationship are obtained systematically in the ranges of 0-90GPa and 0-2000K.