Large-scale multiconfiguration Dirac-Hartree-Fock calculations for astrophysics: Cl-like ions from Cr~VIII to Zn~XIV

TL;DR

This paper presents high-accuracy atomic data for Cl-like ions from Cr VIII to Zn XIV using advanced relativistic calculations, aiding astrophysical spectral analysis and proposing new ion identifications.

Contribution

It provides a comprehensive set of transition energies and radiative data for key astrophysical ions using MCDHF and RCI methods, with validation against MBPT and experimental data.

Findings

High accuracy of excitation energies with uncertainties of a few hundred cm$^{-1}$

Discrepancies identified in existing experimental energies for Fe X and Ni XII

Several new ion identifications proposed

Abstract

We use the multiconfiguration Dirac-Hartree-Fock (MCDHF) method combined with the relativistic configuration interaction (RCI) approach (GRASP2K) to provide a consistent set of transition energies and radiative transition data for the lower $n =3$ states in all Cl-like ions of astrophysical importance, from \ion{Cr}{8} to \ion{Zn}{14}. We also provide excitation energies calculated for \mbox{Fe X} using the many-body perturbation theory (MBPT, implemented within FAC). The comparison of the present MCDHF results with MBPT and with the available experimental energies indicates that the theoretical excitation energies are highly accurate, with uncertainties of only a few hundred cm$^{-1}$. Detailed comparisons for Fe~X and Ni~XII highlight discrepancies in the experimental energies found in the literature. Several new identifications are proposed.