Structural and Thermodynamic Properties of Perovskite-Type Superconductor ZnNNi₃ by First-Principles Calculations

Abstract

The structural and thermodynamic properties of the non-oxide superconductor ZnNNi₃ are investigated by using ab initio plane-wave pseudo potential density functional theory method within the generalized gradient approximation (GGA). The calculated lattice constants, the bulk modulus and its pressure derivative, and elastic constants of ZnNNi₃ at zero temperature and pressure are in good agreement with the available theoretical and experimental data. The thermodynamic properties of ZnNNi₃ are predicted by using the quasi-harmonic Debye model. The pressure-volume-temperature (P-V-T) relationship, the bulk modulus B₀ and bulk modulus B, the variations of the thermal expansion coefficient α and the heat capacity C_V, C_P with pressure P and temperature T, as well as the Grüneisen parameter-pressure-temperature γ (γ-P-T) relationships are obtained systematically in the ranges of 0–70 GPa and 0–1000 K.