Opportunities for exascale in the characterization of uranium materials

Characterizing new materials or unknown polycrystalline solids is a long-standing challenge for chemists. This problem has new resonance with the nuclear forensics community, where polycrystalline and amorphous materials are regularly encountered. Further, prediction of crystal structures and the calculation of vibrational properties for actinide materials is computationally intensive, limiting the unit cell size and number of structures which can be calculated. By analyzing basic geometric configurations, we hope to isolate spectroscopic characterization of low-symmetry systems to fundamental units. We have performed an analysis of coordination geometries of over 4000 uranium oxide and uranium fluoride structures, generated by combining genetic algorithm searches for stable phases with density functional theory. Here we present progress toward correlating vibrational properties with the fundamental coordination environments, aiming to facilitate interpretation of experimental analytical data from spectroscopy to characterize complex uranium phases. We discuss the opportunities and challenges for exascale computing and actinide materials, with an emphasis on the impacts and importance to the field of nuclear forensics.