Theoretical Study on the Dynamical Stability, Chemical Bonding, and Electronic Properties of LaBH ₈ and LaBeH ₈ Under Pressure

Abstract LaBH 8 and LaBeH 8 , as typical Fm‐3m XYH 8 ‐type hydrides, are predicted with outstanding superconductivity below megabar pressure. Notably, LaBeH 8 has been successfully synthesized with the predicted XYH 8 ‐type structure and measured to have a critical temperature of 110 K down to 80 GPa. Here, the dynamically stability, chemical bonding, and electronic properties of LaBH 8 and LaBeH 8 are systematically investigated under pressure through first‐principles calculations. Dynamical stability calculations show that removing B or Be atoms will make the structure be unstable at 80 GPa, suggesting the critical role of these atoms in stabilizing the structure. For LaBH 8 , the calculated electron localization function (ELF), crystal orbital Hamilton population (COHP) and its integrals, topological analysis of the all‐electron charge density and projected electronic density of states all suggest the presence of strong covalent interactions in the B–H bonds. For LaBeH 8 , COHP analysis and its integrals indicates covalent character in the Be–H bonds, while the ELF and topological analysis suggest that the Be–H bonds also exhibit ionic character. This study provides deep analysis of the chemical bonding for the superconducting LaBH 8 and LaBeH 8 .