First‐Principles Study of High‐Pressure Stability and Superconductivity in LiCe

By employing first‐principles‐assisted CALYPSO structural exploration combined with high‐pressure thermodynamic analysis, this study systematically establishes the phase diagram of the binary Li–Ce system within the 200, 300, and 350 GPa pressure regime. The LiCe phase is identified as metastable at 200 GPa; however, upon further compression to 300 and 350 GPa, it transforms into a thermodynamically stable state. Electronic structure calculations reveal that extreme compression enhances orbital hybridization and electron delocalization, thereby reinforcing the metallic character of the phase. Furthermore, superconducting analysis uncovers a superconductivity mechanism driven by the synergistic coupling between Ce and Li phonon modes. With increasing pressure, the electron–phonon coupling mechanism gradually shifts from being dominated by low‐frequency heavy‐atom (Ce) modes toward enhanced participation of high‐frequency light‐atom (Li) modes. Consequently, the superconducting critical temperatures ( T _c ) of the LiCe phase are calculated to be 3.04, 0.48 and 0.23 K at 200, 300 and 350 GPa, respectively.