Springer Online Journal Archives 1860-2000
Abstract We calculate the density of states for the nondegenerate Anderson model for various values ofu=U/πΔ andn f using the perturbation theory withu as the expansion parameter. Summing all the ω-independent self-energy diagrams, we use the Friedel sum rule and Ward identities to express the physical quantities in terms of the remaining ω-dependent part of the self-energy, which we evaluate to the 2nd order. The results for the spin and charge susceptibilities obtained in such a way compare rather well with the Bethe-ansatz results. The density of states exhibits different features in different parts of the parameter space. In Kondo region (u〉1,n f ≅1, i.e., −ε f ~U/2≫Δ), we obtain a many-body resonance (half-width ∼T K ) around the Fermi level and two broad peaks (∼Δ) at about ε f +n f U and ε f +U. In the VF region (u〉1, and ε| f |≦Δ) we obtain only two peaks (∼Δ), one at about ε f and one between ε f +n f U and ε f +U. The consequences regarding the shape of the photoemission and inverse photoemission spectra of Ce intermetallics are discussed.
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