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Interpolating self-energy of the infinite-dimensional Hubbard model: Modifying the iterative perturbation theory

M. Potthoff·T. Wegner·W. Nolting
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Abstract

We develop an analytical expression for the self-energy of the infinite-dimensional Hubbard model that is correct in a number of different limits. The approach represents a generalization of the iterative perturbation theory to arbitrary fillings. In the weak-coupling regime perturbation theory to second order in the interaction U is recovered. The theory is exact in the atomic limit. The high-energy behavior of the self-energy up to order (1/E)**2 and thereby the first four moments of the spectral density are reproduced correctly. Referring to a standard strong-coupling moment method, we analyze the limit of strong U. Different modifications of the approach are discussed and tested by comparing with the results of an exact diagonalization study.

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M. Potthoff, T. Wegner, W. Nolting. 1997-08-21. Interpolating self-energy of the infinite-dimensional Hubbard model: Modifying the iterative perturbation theory. https://doi.org/10.1103/physrevb.55.16132

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