Exploring Dynamically Stable Li‐Based Novel RELiH 3 (RE = La, Ce, Pr, Nd) Rare Earth Hydrides for Sustainable Energy Applications: A DFT Study

First‐principles density functional theory (DFT) simulations were employed to investigate the structural, electronic, mechanical, optical, and hydrogen storage properties of novel rare‐earth‐based RELiH 3 (RE = La, Ce, Pr, and Nd) hydrides. The optimized lattice constants and negative formation energies confirm their structural and thermodynamic stability, while X‐ray diffraction (XRD) analysis verifies the cubic phase. Both PBE and HSE06 functionals reveal metallic behavior ( E g = 0 eV), supported by the non‐zero total density of states (TDOS) at the Fermi level. Charge population analyses and charge density maps indicate predominantly ionic bonding. The compounds exhibit strong optical absorption in the visible and ultraviolet (UV) regions, high conductivity, and notable dielectric response. Mechanical, phonon, and ab initio molecular dynamics (AIMD) results confirm excellent mechanical strength and dynamic and thermal stability. The RELiH 3 hydrides demonstrate gravimetric H 2 storage capacities of 1.96–2.03 wt% and volumetric capacities of 91–102 gH 2 L −1 . The hydrogen desorption temperatures are 310.05 K for LaLiH 3 , 268.71 K for CeLiH 3 , 302.66 K for PrLiH 3 , and 325.55 K for NdLiH 3 , which meet the U.S. Department of Energy (DOE) targets. These findings highlight RELiH 3 hydrides as promising candidates for solid‐state hydrogen storage applications.