Stability of CaXe₃ under Extreme Conditions

High pressure modifies the valence electron configuration of elements, enabling the formation of compounds with unconventional stoichiometries. In this work, we employ the CALYPSO structure search and density functional theory calculations to explore the structural phase transitions and electronic properties of calcium-xenon compounds under 170-290 GPa. Calculated formation enthalpies identify a Xe-rich CaXe₃ compound that adopts a tetragonal P4/mmm phase at 170 GPa and transforms to a monoclinic C2/m phase near 220 GPa. Electronic property calculations confirm that both phases are metallic. Ab initio molecular dynamics simulations indicate solid-like behavior at the sampled conditions between 170 and 290 GPa and at temperatures up to 9,000 K. The predicted stability range overlaps with pressure-temperature conditions expected in the deep interiors of rocky super-Earths, suggesting that CaXe₃ may serve as a potential Xe-bearing phase in such environments. These findings deepen our understanding of the high-pressure chemistry of inert-element-containing compounds and lay a theoretical foundation for discovering new alkaline earth metal-noble gas compounds.