Exploring magnetic order in actinide dioxides using adiabatic connection fluctuation dissipation theory

Nakamura, Hiroki  ; Machida, Masahiko  

One of the most reliable simulation methods for predicting the physical properties of actinide dioxides is density functional theory (DFT). DFT can evaluate various physical properties including magnetism, but does not always succeed in predicting the correct magnetic ordering. For example, although plutonium dioxide is nonmagnetic, the ground state calculated by DFT is magnetic even if the strong correlation effect and spin-orbit coupling are considered. To address this issue, we adopt adiabatic connection fluctuation dissipation theory (ACFDT), which is expected to be more effective for actinides dioxide since it considers higher-order correlation and exchange interaction effects more efficiently. In this paper, we calculated energy for PuO and UO with ACFDT for various magnetic orders and evaluated the ground-state magnetic order. We found that ACFDT is more likely to predict the correct magnetic order than DFT. Thus, it is expected that ACFDT can improve the accuracy in the prediction of the physical properties of fuel materials.