Insights of pressure-mediated optoelectronic, vibrational and thermodynamic properties of APdH3 (A = Ca, Sr, Ba) perovskite hydrides from ab initio calculations

Abstract

This report presents the electronic, optical, vibrational, and thermodynamic properties of APdH₃ (A = Ca, Sr, Ba) perovskites across the pressure range of 0 GPa–50 GPa employing ab initio calculations based on density functional theory. The computed electronic structures display the metallic behavior of these hydrides under both ambient and pressurized conditions. The electronic dispersions are strongly influenced by applied pressures. The pressure-induced optical properties demonstrate that the optoelectronic characteristics can be tuned by varying hydrostatic pressure. Phonon dispersion exhibits the dynamical stability of CaPdH₃, and SrPdH₃ hydrides at ambient condition, whereas BaPdH₃ remains unstable under pressure below ∼10 GPa. Utilizing quasi-harmonic Debye approximation, pressure-induced thermodynamic properties are evaluated up to 1000 K. All thermodynamic parameters are significantly affected under pressure in a certain temperature. The Gibbs free energy analyses elucidate that CaPdH₃ possesses the highest thermodynamic phase stability among these hydrides at temperatures up to 1000 K.