This study provides a comprehensive DFT-based investigation of A₂H₃X (A = Sr, Ba; X = Cl, Br) compounds, highlighting their structural, electronic, optical, thermodynamic, and mechanical properties. The results reveal indirect band gaps, strong optical absorption in the visible to UV range, dynamic and mechanical stability, and promising potential for applications in solar energy conversion and solid-state hydrogen storage.

Abstract

This work provides a comprehensive analysis of structural, electronic, optical, thermodynamics, and mechanical properties of A₂H₃X (A = Sr, Ba and X = Cl, Br) compounds using GGA-PBE functional of density functional theory (DFT). Dynamic stability of all compounds is predicted by absence of imaginary frequencies in phonon dispersion analysis. The compounds have shown indirect band gaps for Sr₂H₃Cl (2.12 eV), Sr₂H₃Br (2.13 eV), Ba₂H₃Cl (2.06 eV) and Ba₂H₃Br (2.15 eV), and the contributions of constituent orbitals have been observed to the electronic band structures presented by PDOS, confirming the potential applications in photovoltaic cells. Optical topologies have predicted the high values of absorption, dielectric function and refractive index in visible to UV-range showing potential of these materials for solar energy conversion application. Debye temperature along with other thermodynamic properties have presented the dynamic stability of the compounds. Mechanical properties have shown anisotropic behavior mostly in YZ and XZ directions. The Pugh's and Poisson's ratios have described the ductile nature of the compounds. The calculated gravimetric hydrogen storage capacity values of the compounds indicate that Sr₂H₃Cl with a content of approximately 1.4 wt%, holds potential as solid-state hydrogen storage material for energy applications, particularly in portable fuel cell systems and renewable energy technologies.