Layered uranium(vi) hydroxides: structural and thermodynamic properties of dehydrated schoepite α-UO2(OH)2

Abstract

The structure of dehydrated schoepite, α-UO₂(OH)₂, was investigated using computational approaches that go beyond standard density functional theory and include van der Waals dispersion corrections (DFT-D). Thermal properties of α-UO₂(OH)₂, were also obtained from phonon frequencies calculated with density functional perturbation theory (DFPT) including van der Waals dispersion corrections. While the isobaric heat capacity computed from first-principles reproduces available calorimetric data to within 5% up to 500 K, some entropy estimates based on calorimetric measurements for UO₃·0.85H₂O were found to overestimate by up to 23% the values computed in this study.