Inelastic Neutron Scattering and Density Functional Theory for Uranium Compounds

Modern computational tools, specifically density functional theory (DFT), have enhanced the utility of many experimental techniques. Here, we discuss the application of DFT to inelastic neutron scattering (INS) phonon density of states measurements of two U-bearing compounds, UO₂F₂ and UF₄. Neutrons offer an exceptional advantage for UO₂F₂, whose hygroscopic nature localizes environmental water, because of the relative sensitivity of neutrons to H compared to the high Z U crystal backbone. Likewise, UF₄ has a weak Raman and infrared activity, but a reasonable neutron cross-section. Combined with a novel computational approach developed at the Spallation Neutron Source, we can directly calculate the dynamic structure factor from DFT calculations and identify regions of special interest based on agreement or disagreement between experiment and theory.