First-principles study of elastic and electronic properties of layered ternary nitride SrZrN₂ under pressure

The structural, elastic, and electronic properties of SrZrN2 under pressure up to 100 GPa have been carried out with first-principles calculations based on density functional theory. The calculated lattice parameters at 0 GPa and 0 K by using the GGA-PW91-ultrasoft method are in good agreement with the available experimental data and other previous theoretical calculations. The pressure dependence of the elastic constants and the elastic-dependent properties of SrZrN2, such as bulk modulus B, shear modulus G, Young's modulus E, Debye temperature Θ, shear and longitudinal wave velocity VS and VL, are also successfully obtained. It is found that all elastic constants increase monotonically with pressure. When the pressure increases up to 140 GPa, the obtained elastic constants do not satisfy the mechanical stability criteria and a phase transition might has occurred. Moreover, the anisotropy of the directional-dependent Young's modulus and the linear compressibility under different pressures are analysed for the first time. Finally, the pressure dependence of the total and partial densities of states and the bonding property of SrZrN2 are also investigated.