Configuration Interaction in the Spectrum of Sr III

Least-squares fits to the 4 s 2 4 p 5 ( n + 1) s + 4 s 2 4 p 5 nd + 4 s 4 p 6 5 p and the 4 s 2 4 p 5 ( n + 2) p + 4 s 2 4 p 5 nf + 4 s 4 p 6 4 d configurations of Sr III are presented. The latter configurations are found to interact strongly whereas the interactions between the former are relatively small. In particular, the 4 s 2 4 p 5 nf ↔ 4 s 4 p 6 4 d interaction causes large distorsions of the level distribution in 4 s 2 4 p 5 nf . The fitted parameter values are compared to Hartree-Fock results. The fitted 4 s 2 4 p 5 nd ↔ 4 s 4 p 6 5 p and 4 s 2 4 p 5 nf ↔ 4 s 4 p 6 4 d configuration interaction parameters are more than a factor of two smaller than the Hartree-Fock values.