DFT calculations on heat capacity and Debye temperature of Cs2GeF6 perovskite under high temperature and pressure.

Halide perovskites have attracted attention owing to their extraordinary electronic, thermodynamic, optical, and thermoelectric properties and their promising applications in solar cells, optoelectronic and thermoelectric. We have performed a study on inorganic halide perovskite Cs₂GeF₆ for understanding thier thermophysical behavior using comprehensive density functional theory (DFT) with full-potential linearized augmented plane wave (FP-LAPW) implemented in WIEN2K code. The generalized gradient approximation (GGA) has been used as exchange-correlation potential to solve the Hamiltonian of the above problem. The studied perovskite is crystallized in the cubical Fm-3m (225) phase. For thermodynamic properties, heat capacity at constant volume C_v and Pressure C_P, adiabatic bulk modulus BS, and Debye temperature θ_D have been estimated using the quasi-harmonic Debye model implemented in Wien2k code. Further, their variations for high temperature and pressure have been carefully examined. [ABSTRACT FROM AUTHOR]