Magnetic ground state of plutonium dioxide: DFT+U calculations

Abstract

The magnetic states of the strongly correlated system plutonium dioxide (PuO2) are studied based on the density functional theory (DFT) plus Hubbard U (DFT+U) method with spin–orbit coupling (SOC) included. A series of typical magnetic structures including the multiple-k types are simulated and compared in the aspect of atomic structure and total energy. We test LDA, PBE, and SCAN exchange–correlation functionals on PuO2 and a longitudinal 3k antiferromagnetic (AFM) ground state is theoretically determined. This magnetic structure has been identified to be the most stable one by the former computational work using the hybrid functional. Our DFT+U + SOC calculations for the longitudinal 3k AFM ground state suggest a direct gap which is in good agreement with the experimental value. In addition, a genetic algorithm is employed and proved to be effective in predicting magnetic ground state of PuO2. Finally, a comparison between the results of two extensively used DFT+U approaches to this system is made.