Effects of magnetic ordering on the ground-state energy of plutonium dioxide; A Study using adiabatic connection fluctuation-dissipation theory

Nakamura, Hiroki  ; Machida, Masahiko  

Efficiency and safety improvements in nuclear fuel development demand a comprehensive understanding of the thermal properties of PuO. Because of difficulty of experiments at high temperatures, they have been supplemented by numerical simulations, such as density functional theory (DFT). While DFT struggles to replicate the nonmagnetic insulating ground state of PuO, DFT+U can reproduce nonmagnetic insulating state. However, the obtained state remains less stable than magnetic states and is not the ground state. Adiabatic connection fluctuation-dissipation theory (ACFDT) is expected to be a promising solution, addressing higher-order correlations and exact exchange energies. In this study, we evaluate the ground state energy using ACFDT and find that the nonmagnetic state can be the ground state. This result successfully reproduces the observed nonmagnetic ground state of PuO and has the potential to improve predictions of the thermal properties of nuclear fuel materials.