Structural, Electronic, Mechanical, Dynamical, and Optical Properties of KX ₃ H ₈ (X = Sc, V, and Cr) Hydrides: A DFT Perspective

ABSTRACT This study investigates the structural, mechanical, electronic, optical, dynamical, and hydrogen storage properties of potassium‐based hydrides (X = Sc, V, Cr) using density functional theory within the CASTEP code. All compounds crystallize in the cubic space group and exhibit good thermodynamic stability, with formation energies of , , and eV/atom for , , and , respectively. The calculated gravimetric hydrogen storage capacities reach 4.43%, 4.03%, and 3.9%, highlighting their potential for solid‐state hydrogen storage applications. Mechanical stability is confirmed by the Born criteria, with showing the highest stiffness due to its larger shear and Young's moduli. Electronic band structures and densities of states computed using both GGA‐PBE and the hybrid HSE06 functional reveal metallic behavior for all compounds. Optical properties, including dielectric response and absorption characteristics, indicate strong interaction with electromagnetic radiation, particularly for . These findings suggest that hydrides are promising multifunctional materials for hydrogen storage and energy‐related applications.