Multiconfiguration Dirac–Fock calculations of excitation energies and wavelengths in highly charged tungsten ions

Abstract

The fully relativistic multiconfiguration Dirac–Fock (MCDF) method is employed to calculate the excitation energies and wavelengths for nine isoelectronic sequences of tungsten ions. In calculations, electron correlations, quantum electrodynamical (QED) effect, and Breit correction are taken into account. The core–valence and valence–valence corrections are analyzed in a systematic way. The core setting was systematically studied for four cases of one electron occupying the outermost s orbital, one electron occupying the outermost p orbital, three electrons occupying the outermost p orbital, and one electron occupying the outermost d orbital. In our research, at least two calculation models are adopted for every tungsten ion. Through analyzing our results, it is found that the following three calculation models can help to get results closer to measured values: (i) setting the closed shells as core; (ii) taking core–valence corrections into account when there is only one valence electron; (iii) taking valence–valence corrections into account when the number of valence electrons is not less than three. The purpose of this paper is to provide some references on configuration selection and configuration interaction in calculations for a multi-electron system of highly charged tungsten ions.