Breit and QED effects on the 3d9D3/22→2D

Abstract

The multiconfiguration Dirac-Hartree-Fock theory is used to calculate the 3d 9 2 D 3/2 → 2 D 5/2 transition energy for Co-like ions with Z = 28 − 100. We investigate how electron correlation, frequency-independent and -dependent Breit interaction, as well as QED corrections vary along the sequence. The well understood frequency-independent Breit contribution has the largest contribution for all ions. Among the corrections to this, correlation decreases rapidly with Z, the frequency-dependent Breit contribution is important especially for high-Z ions, and the Self-energy contribution to the QED becomes the largest correction already for Z > 50. We evaluate and compare results for the Self-energy in three different approximations, (i) the approach implemented in the GRASP2K package, (ii) the method based on Welton's concept and (iii) a model operator approach recently developed by Shabaev and co-workers. Through comparison with experimental values, it seems that the third set of results have the best agreement with experiments, but the difference from experiments for high-Z ions, is around 0.03%-0.04%, and therefore our results are outside the error bars of the experiments.

Benchmarking calculations with spectroscopic accuracy of excitation energies and wavelengths in sulfur-like tungsten

“…We compared the performance of three different quantum electrodynamic (QED) potentials [13,14] to estimate the accuracy of QED calculations, and reported improved theoretical excitation energies and transition wavelengths for W 58+ by at least one order of magnitude. The accuracy of the MCDHF-RCI calculations [11] allowed the authors to assign the unidentified line at λ = 34.779(4) Å from [9] to the M1 transition 3s 2 3p 4 1 D 2 → 3s 2 3p 4 3 P 2 of S-like W. The present study is an extension of our recent work on W 58+ [11].…”

QED radiative corrections to the P1/22−P3/22

“…However, despite these examples, it is still not clear how accurate the QED contributions obtained by such approaches are. In particular, in recent papers of Li et al [41] and Si et al [42] accurate theoretical calculations have been performed for the ground-state transition energies in F-like and Co-like ions and have shown that the correlation effects are strongly reduced by so-called Layzer quenching effect [43,44]. Thus, the accurate account for the correlations becomes possible for these transitions and this allows one to test the QED corrections.…”

Breit and QED contributions in atomic structure calculations of tungsten ions

“…This effect is about 1 eV (0.1-0.3%) in studied cases. However, it has been found that "variational effect" is significantly reduced when active space is expanding [50,51]. The frequency-dependent Breit term is about 2% of frequency-independent one (having opposite sign).…”