Photoionization of atomic scandium in the ground state:  Total cross sections and $3\overrightarrow{p}3d$ resonances

A methodology is developed combining many-body-perturbation theory and close coupling of final-state channels with multiconfiguration Hartree-Fock theory to calculate photoionization cross sections of open-shell atoms with accurate threshold and resonance energies. Photoionization calculations of the ground ${1s}^2{2s}^2{2p}^6{3s}^2{3p}^6{3d4s}^{2}D$ state of atomic Sc, the first of the transition metals, are performed from threshold to 60 eV using this method. All single-electron transitions from $4s,$ $3d,$ and $3d$ subshells are included. Over a broad region of energy, the cross section is dominated by the strength of the $3\overrightarrow{p}3d$ resonances which are split into nine distinct transitions through the angular momentum coupling with the open shells. The total cross section and the $3\overrightarrow{p}3d$ resonances are presented in detail and reasonably good agreement with available experiment, for both energies and cross section, is obtained. Classifications of a number of the $3\overrightarrow{p}3d$ resonances are proposed. In the low-energy region, good agreement with a previous R-matrix calculation is found.