Inter-configuration fluctuation for 5f electrons in uranium hexafluoride: A many-body study

Abstract

A quantum mechanics calculation is performed on uranium hexafluoride (UF6) by using density functional theory (DFT) combing with dynamical mean-field theory (DMFT) scheme, taking into account the spin–orbit coupling (SOC) interaction and the on-site 5f-5f Coulomb repulsion. Results demonstrate that SOC-splitting j = 5/2 and j = 7/2 manifolds are in the metallic and insulating regimes, respectively, albeit both are in weakly correlated states. Ratio of the quasi-particle weights R = Zj=7/2/Zj=5/2 is about 1, suggesting that UF6 is not in the so-called orbital-selective localized state. Russel-Saunders (LS) coupling scheme is feasible for U 5f electrons. U 5f-conduction electrons hybridization, 5f-5f correlation, SOC interaction and final state effects yield a complicated spectrum function. Occupation probability analysis shows that 5f electrons exhibit the so-called inter-configuration fluctuation (ICF) due to admixing of 5f1 and 5f3 atomic configurations into 5f2 configuration with an average occupation number of n5f ∼ 1.8585, mainly arising from the complicated quantum mechanics processes including the dual nature of localized and itinerant 5f electrons, a quantum mechanical mixture of the energetically degenerate 5fn configurations, as well as the flexible outer electronic configuration of U ions. Finally, the momentum-resolved electronic spectrum function (the so-called quasiparticle band structure) is also discussed.