Theoretical study on superconductivity of Ce-Ca-H ternary hydrides under high pressure

In this work, we used genetic algorithm combined with density functional theory (DFT) calculations to search for the structures of the pressure-induced ternary hydrides CeCaxHy (x=1-3, y = 1-24). The crystal structures and electronic properties of CeCaxHy in the pressure range of 100-300 GPa were systematically studied. The calculated results showed that structures of P4/mmm-CeCaH8, Cmmm-CeCaH8, Cmmm-CeCaH12 and Fm-3mCeCa3H24 could be stable in pressure range of 150-300 GPa. The predicted superconducting transition temperature (Tc) values were 90, 86 and 150 at 150 GPa for P4/mmm-CeCaH8, Cmmm-CeCaH8 and Cmmm-CeCaH12, respectively, and the Fm-3m-CeCa3H24 structure had a Tc of 201 K at 300 GPa. Also, the mechanical properties of the Ce-Ca-H most stable phases were discussed.