PNNL

Abstract

A systematic comparison of the structures and electronic and optical properties of U3O8 in the c2mm, P¯62m, and P21/m structures (the a, ß, and ? phases, respectively) is performed using density functional theory + U (PBE + U) and the Heyd–Scuseria–Ernzerhof screened hybrid functional (HSE). The relationship between the semiconducting C2mm phase of U3O8 and the high temperature, metallic P¯62m phase is explored in more detail. Our calculated results show that the HSE functional gives a better description of the electronic and optical properties when compared with available experimental data for the a and ß phases, but neither approach does particularly well for the high pressure ? phase.