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Session M13 - Correlated Metals - Theory I.
MIXED session, Thursday morning, March 21
Room 240, America's Center
In the framework of direct perturbation theory a fully self-consistent approximation beyond the well known NCA will be presented for the Anderson Model. The resummation of a class of skeleton diagrams up to infinite order in V includes all contribution up to the order O(1/N^2) ( N = degeneracy of the magnetic state). Qualitative improvements in maintaining local Fermi-Liquid relations and one particle spectral properties in comparison to the well known NCA will be reported. The location and temperature dependence of the AS-resonance for the case N=2 is found to be rather close to the chemical potential in excellent agreement with Friedel's sum rule; the static magnetic susceptibility exhibits the same N-dependence as the exact bethe-ansatz solution ( F B Anders, N Grewe, Europhys. Lett. )26, 551 (1994), F B Anders, J. Phys.: Condens. Matter 7, 2801 (1995) . This Post-NCA theory is used to obtain spectral functions in the framework of the LNCA for the Anderson lattice model, which is believed to be the appropriate microscopic description of Heavy-Fermi systems.
