Self-consistent density functional calculations of the crystal field   levels in lanthanide and actinide dioxides
  Using a recently developed method combining a nonspherical self-interaction corrected LDA+$U$ scheme and an on-site multi-body Hamiltonian [Phys.\ Rev.\ B 83, 085106 (2011)], we calculate the crystal field parameters and crystal field (CF) excitation levels of $f$-element dioxides in the fluorite structure with $f^{n}$ electronic configurations, including $n=1$ (PaO$_{2}$, PrO$_{2}$), $n=2$ (UO$_{2}$), $n=3$ (NpO$_{2}$), and $n=4$ (PuO$_{2}$). It is shown that good agreement with experimental data (within approximately 10 to 20 meV) can be obtained in all cases. The properties of the multi-electron CF ground states are analyzed. 
Fei Zhou and Vidvuds Ozolins
cond-mat.str-el