The B-spline R-matrix method is used to investigate the photoionization of neutral iron from the ground and excited states in the energy region from the ionization thresholds to 2 Ry. The multiconfiguration Hartree-Fock method in connection with adjustable configuration expansions and term-dependent orbitals is employed for an accurate representation of the initial states of Fe I and the target wave functions of Fe II. The close-coupling expansion contains 261 LS states of Fe II and includes all levels of the 3d6 4s, 3d5 4s2, 3d7, 3d6 4p, and 3d5 4s 4p configurations. Full inclusion of all terms from the principal configurations considerably changes both the low-energy resonance structure and the energy dependence of the background cross sections. Partial cross sections are analyzed in detail to clarify the most important scattering channels. Comparison with other calculations is used to place uncertainty bounds on our final photoionization cross sections and to assess the likely uncertainties in the existing data sets.
Zatsarinny, O., Bartschat, K., Fernandez Menchero, L., & Tayal, S. S. (2019). Photoionization of neutral iron from the ground and excited states. Physical Review A, 99(2), 023430. https://doi.org/10.1103/PhysRevA.99.023430