Perturbative approach to J mixing in f-electron systems : Application to actinide dioxides

We present a perturbative model for crystal-field calculations, which keeps into account the possible mixing of states labelled by different quantum number $J$. Analytical $J$-mixing results are obtained for a Hamiltonian of cubic symmetry and used to interpret published experimental data for actinide dioxides. A unified picture for all the considered compounds is proposed by taking into account the scaling properties of the crystal-field potential.