We probe how pressure tunes the structural, mechanical, electronic, optical, and thermodynamic properties of lithium-based perovskites LiXO ₃ (X = Si, Pr). Under compression, both materials retain their cubic structure, but their physical properties diverge dramatically. LiSiO ₃ becomes stronger and more ductile, its metallic character and melting point maintained under pressure —a signature of a robust, covalently bonded network with band overlap. Its thermal transport, however, shows a high-pressure softening of lattice vibrations. In contrast, LiPrO ₃ responds erratically; with its softer lattice, narrow gap, and anomalous thermal properties fluctuates under stress, which reveals the profound influence of Pr 4 f electrons. These distinct behaviors, including LiPrO ₃ ’s unstable Debye temperature and non-monotonic melting point, signal different technological futures: LiSiO ₃ for high-stress optics and protective coatings, LiPrO ₃ for smart sensors and pressure-switchable electronics. This study maps a course for tailoring perovskite materials by design, linking chemistry to performance under extreme conditions.

The search for effective hydrogen storage materials has stimulated extensive research into compounds with high storage capacity and stability. In this study, we explored lithium-based hydride perovskites, $LiX{H}_3$$(X=Ge,$$Ru)$, as potential candidates for solid-state hydrogen storage applications. Our results reveal that both compounds possess remarkable structural stability, which is confirmed by phonon dispersion analysis, negative formation energies, elementary molecular dynamics simulations (AIMD), and elastic static evaluations. The calculated optoelectronic properties indicate the metallic character of both perovskites. Moreover, the thermodynamic behavior was examined under various temperature and pressure conditions. Importantly, the predicted hydrogen storage characteristics—including gravimetric and volumetric capacities as well as hydrogen desorption temperatures—meet the U.S. Department of Energy (DOE) targets. These findings suggest that $LiX{H}_3$$(X=Ge,$$Ru)$ perovskites are promising materials for sustainable solid-state hydrogen storage, contributing to the advancement of clean and efficient energy technologies.