The influence of core excitations on energies and oscillator strengths of iron group elements

We show that for configurations of the type 3pM3dN the influence of core excitadons, in particular the excitation 3p2 -+ 3 8 , is important both for energies and oscillator suengths.The latter is particularly true for Wansitions of the type 3p63dN -+ 3ps3dN+' due to the fact that the core excitation in the ground configuration leads lo D configuration which has an allowed dipole transition to the excited state.Differences and similarities between 3p53dN and the more extensively studied 3p63dN configurations are pointed out and illustrated with several examples concerning highly charged ions.The conclusion is that.while core excitations are impoLfant for the description of tnnsitions out of the open 3d shell, they are absolutely essential for vnnsitions out ofthe closed 3p shell.gf values are given for astrophysically important transitions in Ni x.