Extended calculations of level and transition properties in the nitrogen isoelectronic sequence: Cr XVIII, Fe XX, Ni XXII, and Zn XXIV^⋆

¹ Institute of Theoretical Physics and Astronomy, Vilnius University, A. Goštauto 12, 01108 Vilnius, Lithuania
e-mail: laima.radziute@tfai.vu.lt
² Group for Materials Science and Applied Mathematics, Malmö University, 20506 Malmö, Sweden

Received: 9 June 2015
Accepted: 10 August 2015

Abstract

Extensive multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for 272 states of the 2s²2p³, 2s2p⁴, 2p⁵, 2s²2p²3l, 2s2p³3l, and 2p⁴3l (l = 0,1,2) configurations in the nitrogen-like ions Cr XVIII, Fe XX, Ni XXII, and Zn XXIV. Valence, core-valence, and core-core electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the NIST database. Landé g_J-factors; hyperfine structures; isotope shifts; and radiative electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transition rates are given for all ions. The accuracy of the calculated energy levels is high enough to facilitate identification of observed spectral lines involving the 2l⁴3l′ configurations, for which experimental data are largely missing.