Comprehensive DFT analysis of Cr-based XCrH3 (X = Li, K, Cs) metal hydride perovskites: Unveiling multifaceted properties and hydrogen storage potential

This study explores the potential of perovskite hydrides XCrH₃ (X = Li, K, Cs) for hydrogen storage materials using density functional theory (DFT). The lattice constants are calculated as 3.35, 3.73, and 4.03 Å for LiCrH₃, KCrH₃, and CsCrH₃, respectively. All materials exhibit half-metallic nature and spin polarized band structure reveals magnetic nature. Mechanical properties shows that all compounds are in good agreement with Born stability criteria and are found to be anisotropic in nature. Formation energies are calculated as −4.139, −3.881, −3.536 eV/atom, and Gravimetric hydrogen storage capacities are found 4.38, 3.11, 1.58 % for LiCrH₃, KCrH₃, and CsCrH₃, respectively. Thermodynamic properties, including phonon dispersion, enthalpy, entropy, free energy, and heat capacity, are calculated. The optical properties including dielectric function, absorption, and refractive index are calculated. The volumetric hydrogen density and desorption temperature is calculated for all compounds. This study provides a theoretical foundation for further research into these materials for hydrogen storage applications.