Theoretical studies of spectroscopic properties of Cm⁴⁺ and Am³⁺

In this paper we report on large-scale multiconfiguration Hartree-Fock and multiconfiguration Dirac-Fock calculations of the fine structures of the Cm⁴⁺ and Am³⁺ ions, both having nominal 5f⁶ electronic configuration. Correlation effects play an extremely important role for both considered ions, and the single-configuration model is proved to be unfit to account for this complex picture. A comparison of the calculated energy levels with the results of spectroscopic measurements shows that theory and experiment are in quantitatively good agreement; the ground state of both ions is predicted to have nonmagnetic character. The accuracy of the results is estimated and discussed.