Variational Theory for Two-Impurity Anderson Model

In order to investigate the competition between the Kondo effect and the intersite magnetic interaction in heavy Fermion systems, two-impurity Anderson model is studied by the variational method. Uniform and staggered magnetic susceptibilities are calculated. The staggered susceptibility χ s is enchanced when the magnitude of the antiferromagnetic coupling J between the two impurities becomes of the order of the Kondo temperature T k (1) of a single impurity. χ s diverges at J∼o(T k (1) ) for an N-fold degenerate orbital model when N→∞