Effective Interactions in the Even Configurations of the Third Spectra of the Iron Group.

Four hundred eighty-three levels belonging to the configurations 3d n + 3d n-14s of all third spectra of the iron group were calculated, and 334 observed levels were fitted to them. In addition to the usually used approximation, we first introduced a complete set of two-body and three-body effective-interaction parameters between 3d electrons. Using only two-body effective interactions, we obtained arms error of 175 cm-1; while the addition of three-body effective interactions reduced the rms error to 46 cm-1. When a parameter representing three-body effective interaction between 3d and 4s electrons was also introduced, the rms error was reduced to 38 cm-1.