Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

TL;DR

This paper reports detailed energy levels, radiative rates, and lifetimes for Fe V, Co VI, and Ni VII ions using a quasi-relativistic approach with extensive configuration interaction, achieving high accuracy and discussing discrepancies in transition data.

Contribution

It provides comprehensive calculations of energy levels and radiative rates for three ions using a large CI wavefunction expansion, improving accuracy over previous methods.

Findings

Calculated energies agree well with measurements.

Discrepancies in radiative rates are due to differing CI and methodologies.

No significant discrepancies found in M1 and E2 transition data.

Abstract

Energy levels, Land\'{e} $g$-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d$^4$, 3d$^3$4s and 3d$^3$4p configurations of Fe~V, Co~VI and Ni~VII. Additionally, radiative rates ($A$-values) have been calculated for the E1, E2 and M1 transitions among these levels. The calculations have been performed in a quasi-relativistic approach (QR) with a very large {\em configuration interaction} (CI) wavefunction expansion, which has been found to be necessary for these ions. Our calculated energies for all ions are in excellent agreement with the available measurements, for most levels. Discrepancies among various calculations for the radiative rates of E1 transitions in Fe~V are up to a factor of two for stronger transitions ($f \geq 0.1$), and larger (over an order of magnitude) for weaker ones. The reasons for these discrepancies have been discussed and mainly are due to the differing amount of CI and methodologies adopted. However, there are no appreciable discrepancies in similar data for M1 and E2 transitions, or the $g$-factors for the levels of Fe~V, the only ion for which comparisons are feasible.