First-principles study on the electronic structure transition of β-UH3 under high pressure

We investigate the electronic properties of stable β-UH3 under high pressure up to 75 GPa within the first-principles DFT + U formalism with pressure-dependent U in a self-consistent calculation, and we find an electronic structure transition at about 20 GPa due to the quantum process of localization and itinerancy for partially filled uranium 5 f electrons. The electronic structure transition is examined from four perspectives: magnetization, band structure, density of states, and 5 f electron energy. On the basis of the density of states of 5 f electrons, we propose an order parameter, namely, the 5 f electron energy, to quantify the electronic structure transition under pressure. Analogously to the isostructural transition in 3 d systems, β-UH3 retains its magnetic order after the electronic structure transition; however, this is not accompanied by volume collapse at the transition point. Our calculation is helpful for understanding the electronic properties of β-UH3 under high pressure.