Ab-Initio Calculations of Level Energies, Oscillator Strengths and Radiative Rates for E1 Transitions in Beryllium-Like Iron

Ahmed El-Maaref,Stefan Schippers,Alfred Müller

doi:10.3390/atoms3010002

Abstract

In the present work, energy levels, oscillator strengths, radiative rates and wavelengths of Be-like iron (Fe\(^{22+}\)) from ab-initio calculations using the multiconfiguration Dirac-Hartree-Fock method are presented. These quantities have been calculated for a set of configurations in the general form \(1s^2\,nl\,n'l'\) where \(n=2,3\) and \(\,n'=2,3,4,5\) and \(l=s,p,d\) and \(\,l'=s, p, d, f, g\). In addition, excitations of up to four electrons, including core-electron excitations, have been considered to improve the quality of the wave functions. This study comprises an extensive set of E1 transition rates between states with different \(J\). The present results are compared with the available experimental and theoretical data.

Highlights

Accurate atomic data for iron ions are of interest in astrophysics, especially for the identification of solar spectra [1,2,3,4], as well as in the physics of controlled fusion [5] and plasma diagnostic [6]
Charro et al [29,30] have calculated some oscillator strengths of Be-like iron up to n = 2, 3 using the relativistic quantum defect orbital (RQDO) method and the multiconfiguration Dirac-Fock (MCDF) method, but there were no Breit corrections included in the calculations
The RSCF calculations were followed by relativistic configuration interaction (RCI) calculations including the Breit interaction Hamiltonian [36]

Summary

Introduction

Accurate atomic data for iron ions are of interest in astrophysics, especially for the identification of solar spectra [1,2,3,4], as well as in the physics of controlled fusion [5] and plasma diagnostic [6]. Del Zanna et al [26] have compiled experimental observations of energy levels and wavelengths, and performed calculations of weighted oscillator strengths for Be-like iron using the non-relativistic SUPERSTRUCTURE program. Santos et al [27] calculated probabilities for transitions from the 1s22s3p 3P0 level for selected beryllium-like ions, from Z = 5 to 92. They used the MCDF method including relativistic effects, QED (quantum-electrodynamics) effects, and correlations up to the 4f subshell, they neglected the Breit interaction. Jian-Hui et al [28] have calculated energy levels, oscillator strengths, transition probabilities and wavelengths of Fe22+ using the MCDF method with the inclusion of vacuum polarization and Breit interaction. The present comprehensive treatment of the Fe22+ atomic structure aims at providing more accurate results than hitherto available

Methods

Results

Conclusion