High precision calculation of odd iron-group systems with orthogonal operators

A parametric description of the 3d(N)4p configurations in the IV to VI spectra of the iron sequence with orthogonal operators is reported. Compared to earlier calculations, deviations between calculated eigenvalues and experimental energies are reduced by an order of magnitude and approach experimental error bars. The claim that the fits are physically meaningful is supported by the regular behaviour of the parameters among neighbouring ions and associated 3d(N) cores, as well as by comparison with ab initio calculated values.