Regular Article – Atomic Physics
Checking the reliability of opacity databases
CEA, DAM, DIF, F-91297, Arpajon, France
2 Université Paris-Saclay, CEA, Laboratoire Matière en Conditions Extrêmes, 91680, Bruyères-le-Châtel Cedex, France
Accepted: 21 March 2023
Published online: 13 April 2023
Mathematical inequalities, combined with atomic-physics sum rules, enable one to derive lower and upper bounds for the Rosseland and/or Planck mean opacities. The resulting constraints must be satisfied, either for pure elements or mixtures. The intriguing law of anomalous numbers, also named Benford’s law, is of great interest to detect errors in line-strength collections required for fine-structure calculations. Testing regularities may reveal hidden properties, such as the fractal nature of complex atomic spectra. The aforementioned constraints can also be useful to assess the reliability of experimental measurements. Finally, we recall that it is important to quantify the uncertainties due to interpolations in density-temperature opacity (or more generally atomic-data) tables, and that convergence studies are of course unavoidable in order to address the issue of completeness in terms of levels, configurations or superconfigurations, which is a cornerstone of opacity calculations.
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