Coulomb (Velocity) Gauge Recommended in Multiconfiguration Calculations of Transition Data Involving Rydberg Series

Asimina Papoulia, Jörgen Ekman, Gediminas Gaigalas, Michel Godefroid, Stefan Gustafsson, Henrik Hartman, Wenxian Li, Laima Radžiute, Pavel Rynku, Sacha Schiffmann, Kai Wang, Per Jönsson

Research output: Contribution to journalArticlepeer-review


Astronomical spectroscopy has recently expanded into the near-infrared (nIR) wavelength region, raising the demands on atomic transition data. The interpretation of the observed spectra largely relies on theoretical results, and progress towards the production of accurate theoretical data must continuously be made. Spectrum calculations that target multiple atomic states at the same time are by nomeans trivial. Further, numerous atomic systems involve Rydberg series,which are associated with additional difficulties. In this work, we demonstrate how the challenges in the computations of Rydberg series can be handled in large-scale multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations. By paying special attention to the construction of the radial orbital basis that builds the atomic state functions, transition data that are weakly sensitive to the choice of gauge can be obtained. Additionally, we show that the Babushkin gauge should not always be considered as the preferred gauge, and that, in the computations of transition data involving Rydberg series, the Coulomb gauge could be more appropriate for the analysis of astrophysical spectra. To illustrate the above, results from computations of transitions involving Rydberg series in the astrophysically important C IV and C III ions are presented and analyzed.

Original languageEnglish
Article number106
Issue number4
Publication statusPublished - 2019

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics
  • Astronomy, Astrophysics and Cosmology

Free keywords

  • Babushkin gauge
  • Coulomb gauge
  • Electric dipole transitions
  • Infrared spectra
  • Length formVelocity form
  • Multiconfiguration methods
  • Rydberg series
  • Rydberg states
  • Spectrum calculations
  • Transition rates


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