Multiconfiguration Dirac-Hartree-Fock and configuration-interaction study of $4d-3p$ x-ray transitions in Cu- and Ni-like tungsten ions

TL;DR

This study uses advanced relativistic computational methods to analyze $4d o 3p$ x-ray transitions in tungsten ions, highlighting the importance of active space selection for accurate results.

Contribution

It demonstrates the impact of active space choices on the accuracy of MCDHF-CI calculations for highly ionized tungsten ions.

Findings

Wavelengths and transition rates depend strongly on active space size.

Extending active space without proper control can degrade result quality.

Careful selection of active space improves computational accuracy.

Abstract

The $4d \to 3p$ x-ray transitions in Cu- and Ni-like tungsten ions have been studied theoretically. The multiconfiguration Dirac-Hartree-Fock (MCDHF) method and the large-scale relativistic configuration-interaction (CI) method have been employed in order to take into account electron correlation effects on the wavelengths and transition rates. It was found that the wavelengths and transition rates obtained from the MCDHF-CI method depend strongly on the size and the type of the active space used in the calculations. It has been found that extending the active space of orbitals without careful control of the configuration state function base does not always lead to good quality MCDHF-CI results for highly ionized tungsten ions.