Density functional theory investigation of the phase transition, elastic and thermal characteristics for AuMTe2(M = Ga, In) chalcopyrite compounds

Abstract

We explored the pressure-induced structural phase transitions and elastic properties of AuMTe₂ (M = Ga, In) using the full-potential linearized augmented plane wave method within the framework of density functional theory, applying both generalized gradient and local density approximations. Thermodynamic properties were further assessed through the quasi-harmonic model. We determined the transition pressures for the phase shift from the chalcopyrite structure to the NaCl rock-salt phase in both AuGaTe₂ and AuInTe₂. Additionally, we calculated and analyzed mechanical properties, such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy, ductility versus brittleness, and hardness for the polycrystalline forms of AuMTe₂ (M = Ga, In). The study also examined how temperature and pressure affect the Debye temperature, heat capacities, thermal expansion, entropy, bulk modulus, Grüneisen parameter, and hardness, utilizing the quasi-harmonic Debye model.

Keywords: Au-based chalcopyrite materials; DFT; Debye model; density functional theory; elastic properties; first principles calculation; transition pressures.