First-principles calculations of elastic and thermodynamic properties under hydrostatic pressure of cubic InNxP1-x ternary alloys

摘要

We present a first-principles study of the elastic and thermodynamic properties of the zinc-blend (ZB) InNxP1-x ternary alloy in the full range of 0 <= x <= 1. Calculations were carried out using WIEN2k code based on a non-relativistic full potential linearized augmented plan wave (FP-LAPW) method within the density functional theory (DFT). The approximation of exchange-correlation energy was performed with Generalized Gradient Approximation (GGA). The elastic constants and related mechanical properties were investigated. We have found that the stiffness coefficients increase with the increase of nitrogen content. The values of the bulk modulus derived from elastic stiffness coefficients are found to be very close to the values derived directly from Murnaghan equation of state, indicating the good accuracy of the C-ij coefficients. The elastic properties were also calculated under hydrostatic pressure for (P = 0.00, 5.00, 10.0, 15.0, 20.0, 25.0 GPa). Furthermore, we have performed a quasi-harmonic Debye model calculation using GIBBS2 package to predict the thermodynamic properties and their dependences on the temperature and pressure. Thermodynamic parameters such as the Gibbs free energy, entropy, heat capacity and Debye temperature have been investigated. Our results show a good agreement with available theoretical and experimental data.