DFT Study of Physical Properties for A ₂ H ₃ X (A = Sr, Ba; X = Cl, Br) Compounds: Their Possible Applications for Hydrogen Storage and Optoelectronic Devices

Abstract This work provides a comprehensive analysis of structural, electronic, optical, thermodynamics, and mechanical properties of A 2 H 3 X (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 Sr 2 H 3 Cl (2.12 eV), Sr 2 H 3 Br (2.13 eV), Ba 2 H 3 Cl (2.06 eV) and Ba 2 H 3 Br (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 Sr 2 H 3 Cl 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.