Theoretical Study of the Elastic, Electronic, and Thermodynamic Properties of the Cs2MF6 (M = Cr and Mo) Perovskites

Ab initio calculations have been performed on the structural, electronic, elastic, and thermodynamic properties of compounds Cs2MF6 (M = Cr and Ni) using the density functional theory (DFT) at the Perdew-Burke-Ernzerhof (PBE) functional. The elastic constants of the two compounds have been estimated and the values estimated verify the stability criteria, suggesting that both compounds are stable. The electronic properties of the compounds indicate that compound Cs2CrF6 is a semi-metal, while compound Cs2NiF6 behaves as a semiconductor. Using the quasi-harmonic Debye model, the thermodynamic properties of compounds Cs2CrF6 and Cs2NiF6, such as the heat capacity (CV) and the thermal expansion (alpha), have also been calculated and their obtained values are analyzed and discussed. The effect of pressure and temperature on the mechanical and thermodynamic parameters has also been examined in detail in this study.