Article révisé par les pairs
Résumé : The procedure for calculating the centroid energies as well as the total and partial widths of the generalized seniority distributions of mixed configurations of identical nucleons is described. An extensive use of the quasispin formalism is made. In some particular cases, analytical formulae, some of which are new, are derived for the centroids and widths. Numerical calculations are performed in the nickel and tin isotopes. They show that although the admixtures with