Effective interactions in the even configurations of the third spectra of the iron group

Fo ur hundred e ighty-three le vels be lo ngin g to the co nfi guration s 3d" + 3d'<-l4s of all third spectra of th e iron groUl) we re calc ulated , and 334 observ ed le ve ls we re fitt e d to th e m. In addi ti on to the us u a ll y used a pproximati on, we firs t introdu ced a co mpl e te set of twobody and three-body e ffecti ve-int e rac ti on param e ters between 3d e lec trons. Us in g o nl y tw o bod y e ffec tiv e interac ti ons, we obt a ine d a rm s e rror of 175 c m -I ; whil e the a ddition of threebody e ffec tive inte racti ons redu ced th e rm s e rror to 46 c m -I . Wh e n a p a ram ete r re prese ntin g three-bod y e ffective int erac ti on be tw ee n 3d a nd 4s e lec trons was also in trod u ce d , th e rm s e rror was re du ce d to 38 c m -I