Theoretical Study on Fe-Se-H Hydrides under High Pressure

Iron hydrides can be formed under high pressure and have special physical and chemical properties. Structures and stabilities of FeXSeHY (X = 1-2, Y = 1-6) hydrides under high pressure were studied using a genetic algorithm method combined with DFT calculations. Further, using triangular phase diagrams, we found that the C2/m-FeSeH is most stable among FeSeH1-6 at 150 GPa. Among Fe2SeH1-6, the enthalpy values of Amm2- and I4/mmm-Fe2SeH2 phases are the lowest at 150 and 200 GPa, respectively, and the Immm-Fe2SeH phase is the lowest in enthalpy at 250-300 GPa. The predicted superconducting transition temperatures (T-c) show that C2/m-FeSeH and Amm2-Fe2SeH2 have almost no superconductivity, while the predicted T-c values of I4/mmm-Fe2SeH2 and Immm-Fe2SeH at 150 GPa are 8.6 and 1.1 K, respectively, and that of Pm-FeSeH6 at 150 GPa is 34.4 K.