Atomic data from the IRON project .20. Photoionization cross sections and oscillator strengths for Fe I

Large-scale close coupling calculations for photoionization cross sections and dipole transition probabilities for Fe I are reported. The calculation included 52 LS terms of the target ion Fe II dominated by the configurations 3d(6)4s, 3d(7), 3d(6)4p, 3d(5)4s(2), and 3d(5)4s4p. The eigenfunction expansion of Fe II accounts for the photoionization of the outer 4s subshell, as well as the open inner 3d subshell, of the ground state 3d(6)4s(2 5)D of Fe I. The results include energy levels for 1,117 LS bound states of Fe I, with n less than or equal to 10 and l less than or equal to 7, 32 316 dipole oscillator strengths for transitions among the LS multiplets, and detailed photoionization cross sections, with extensive resonance structures, for all computed bound states. The present photoionization cross section for the ground state is up to three orders of magnitude higher than earlier results from central field type approximations, but it agrees reasonably well with the cross section previously calculated using many-body perturbation theory.