Configuration-Mixing-Driven Quasiparticle Multiplets in Curium Trichloride: Insights from Single-Particle Approximations and a Many-Body Approach

The electronic properties of curium trichloride (CmCl3) are studied using single-particle approximations and a many-body approach in this work. The imaginary parts of the Matsubara Green's functions suggest that 5f(j=5/2) and 5f(j=7/2) manifolds are both in the conducting states, together with the very weak Cm 5f-conduction electron hybridization and localized 5f-derived spectra feature near the Fermi level. The ratio of the quasi-particle weights R = Z(j=7/2)/Z(j=5/2) is larger than 1.0, implying that CmCl3 is in the orbital-selective localized state. The intermediate coupling (IC) mechanism is suitable for the angular momentum coupling of Cm 5f electrons. The admixing of 5f(7) and 5f(8) configurations would give rise to the interconfiguration fluctuation (5f(7.365)) and the mixed-valence state (Cm2.635+) of Cm ions, which could account for the configuration-mixing-driven quasiparticle multiplets in CmCl3. The 5f(n)-mixing-driven interconfiguration fluctuation might be due to the quantum mechanics processes such as the coexistence of the localized and itinerant 5f electrons and the flexible electronic configuration of Cm ions. Finally, the so-called quasiparticle band structure is also predicted.