Energy levels below the ionization threshold for Sc ix, calculated by FAC. Abscissa is the total angular momentum degeneracy 2J + 1 multiplied by  + 1/−1 for even/odd levels, respectively. Black dots represent the levels from the NIST database. The lowest levels configurations are named according to their parent core: nl means 3s²nl (blue); nl′ means 3s3pnl (green); nl′′ means 3p²nl (magenta). First ionization thresholds (levels of Sc x) are also shown.