3 Radiative calculations

The present calculations were carried out in LS coupling, since it is expected relativistic effects in photoionizing the low ionization stages of iron peak elements should be small. Although they might be significant for some transitions, it would be impractical at this stage to carry through a large-scale relativistic calculation involving a number of channels several times larger than the already huge value used in the LS coupling case. Also, the inclusion of fine structure has only a marginal effect on the calculation of the Rosseland or the Planck mean opacities (Seaton et al. 1994).

The second summation in the CC expansion (Eq. (1) represents short range correlation functions. These functions are very important in obtaining accurate (e + ion) wavefunctions, but may cause pseudoresonances, particularly if the two summations in Eq. (1) are inconsistent (Berrington et al. 1987). The present calculation includes all the configurations that result by adding an electron to the target configurations.

The whole calculation was divided into three groups of total (e + ion) symmetries $SL\pi$ according to their multiplicity, i.e. (2S+1) = 2, 4, and 6. For each multiplicity we consider total angular momenta L = 0 - 7, for both parities.