DFT + Study of Plutonium Hydrides with Occupation Matrix Control.

The magnetic order of plutonium hydrides (PuH) has long been a subject of controversy, both experimentally and theoretically. The magnetic, structural, electronic, and thermodynamic properties of PuH are investigated using Hubbard-corrected density functional theory (DFT + ), with derived from linear response calculations. To address the issue of electronic metastable states within DFT + , we employ an occupation matrix control method as well as allowing 5f orbitals to break the structural symmetry. This advanced computational approach establishes that the ground-state magnetic order for PuH is antiferromagnetic and that for PuH is ferromagnetic, consistent with Faraday and nuclear magnetic resonance experiments. Using the conventional hydrogen-vacancy model for PuH, the hydrogen-content-induced magnetic transition and anomalous variation of the magnetic moment are successfully reproduced. In particular, the calculated transition point of matches the experimental findings. Furthermore, the electronic configuration of the Pu atom in PuH is determined to be 5f, which is consistent with observations from X-ray photoemission spectroscopy. Our calculated values for enthalpy of formation, heat capacity, and entropy are in good agreement with experimental data, thereby validating the robustness of our theoretical framework.