1 N CORRECTIONS TO THE BINDING-ENERGY OF AN ANDERSON MODEL FLUCTUATING BETWEEN 2 MAGNETIC CONFIGURATIONS/

We investigate the binding energy separation between the many-body gro und-state singlet and higher-lying magnetic states for the f1-f2 Ander son model to next-leading order in the 1/N expansion, where N denotes the orbital degeneracy of the f states. We formulate integral equation s for the magnetic-state amplitudes that appear at next-leading order in 1/N and solve these, together with the integral equations that desc ribe the singlet, numerically. We find that the total separation betwe en magnetic and singlet states is small, even in the valence-fluctuati on regime, and hence demonstrate the robustness of the leading-order r esult. We find that the maximum binding-energy separation is shifted t owards higher valence, in contradiction to results of the minimal-dege neracy model. We also present results for the valence and charge susce ptibility.