DescriptionPlutonium (Pu) undergoes corrosion via oxygen and hydrogen forming PuO2 and PuHx, respectively. The pyrophoric nature of PuHx and its ability to catalyse the oxidation reaction of Pu leads to a subsequent volume increase placing the storage vessel under mechanical strain potentially leading to containment failure, make it species of interest. A discrepancy on the magnetic order of PuH2 is present in the experimental literature with both antiferromagnetic (AFM) and ferromagnetic (FM) order reported. Experimental studies are hindered by the radioactivity and toxicity of Pu therefore experimental publications on PuHx are scarce. Computational studies, based on density functional theory (DFT), offer valuable into hazardous and challenging materials. The dispute on the magnetic order of PuH2 is also stated DFT studies with only a very small difference in energy (10-2 eV) present between AFM and FM orders. We employ DFT at two levels of theory, PBEsol+U+SOC and HSE06sol+SOC, utilising spin-orbit coupling, on-site Coulombic correction and noncollinear magnetism. To determine the magnetic nature of both cubic PuH2and PuH3 we imposed FM, longitudinal AFM and transverse AFM orders in the <111>, <110> and <100>directions. Using PBEsol+U+SOC, we sampled the Hubbard correction U between 0 – 7 eV finding the magnetic order of both cubic PuH2 and PuH3 dependant on the value of U with a swap in magnetic order41predicted in both structures. When employing HSE06sol+SOC, the most stable magnetic orders for PuH2and PuH3 were FM in the <110> and <111> directions respectively, the energy difference between FM and AFM orders is tiny (10-2- 10-3 eV) in agreement with the literature.
|7 Sep 2022
|CCP5 Annual General Meeting 2022, 42nd edition
|Huddersfield, United Kingdom
|Degree of Recognition