Structural phase transition, elastic constants and thermodynamic properties of TmAs: A DFT study

Abstract

Employing the all-electron full-potential linearized augmented plane wave method and the local density approximation, we report on the results of the structural stability, phase transition pressure, thermodynamic, elastic, electronic and magnetic, properties of thulium arsenide (TmAs). The computed structural parameters, bulk modulus are compared with experimental and other theoretical values. It is found that TmAs undergoes a first-order phase transition from the NaCl-type structure to the CsCl-type structure at approximately 32.96 GPa, corresponding to a volume collapse of around 6.8% during this transition. We have also calculated some elastic properties such as Young modulus, anisotropy factor, and Poisson ratio. The Vickers hardness was predicted using two empirical expressions, which give the shame result ∼5.40 GPa. To gain further information, we used the quasi-harmonic approximation to calculate some thermodynamic properties such as the constant-volume specific heat capacity, the Debye temperature and the entropy of our material of interest. The authors’ results show a monotonous change of the thermodynamic properties of TmAs against temperature. These accords well with the general behavior commonly reported in the literature. The band structure and corresponding density of states have also been determined and analyzed using LSDA, LSDA + U and mBJ-LSDA + U approaches.