Crystal structure prediction of uranium hydrides at high pressure: A new hydrogen-rich phase

Highlights: • Three UH_x phases are predicted, including UH₁₇ with large quantity of hydrogen. • Each U atom transfers more than 1 electrons to the surrounding hydrogen atoms. • The correlation effect is nonsignificant in the three predicted phases. - Abstract: Uranium hydride is a novel hydrogen-rich system which contains 5f electrons. Uranium hydride can not only be used in the nuclear fuel industry, but also be a candidate of high superconducting-temperature materials. In this paper, we have searched the stable uranium hydride structures by using particle swarm optimization method and first-principles calculations. Besides UH₈ and UH₉, we find that UH₁₇, which contains larger hydrogen content than most hydride materials reported before, is also stable at high pressure. The atomic structures, electronic structures and phase diagram of uranium hydrides are provided, and we find that all of the discovered uranium hydrides are metals with negligible magnetic moments.