A First-Principles Study of L-Shell Iron and Chromium Opacity at Stellar Interior Conditions

An unresolved disagreement remains between experimental measurements and theoretical predictions of the L-shell opacity of iron at solar interior conditions. Recently developed free-energy density functional theory (DFT)-based methodology for calculations of optical properties of warm dense matter¹ has been applied for calculations of L-shell opacity of iron and chromium at T = 182 eV. Our DFT predictions are compared to the radiative emissivity and opacity of the dense plasma model,² the real space Green’s function method, and experimental measurements.^3,4 Good agreement is found between all three theoretical methods and in the bound-continuum region for Cr when compared to the experiment, while the difference between direct DFT calculations and the experiment for Fe remains essentially the same as for plasma-physics models.

1 V. V. Karasiev and S. X. Hu, Phys. Rev. E 103, 033202 (2021).

2 G. Miloshevsky et al., Phys. Rev. E 92, 033109 (2015).

3 J.E. Bailey et al., Nature 517, 56 (2015).

4 T. Nagayama et al., Phys. Rev. Lett. 122, 235001 (2019).