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Perturbation expansion for 2-D Hubbard model

V. Zlatic·B. Horvatic·B. Dolicki·S. Grabowski·P. Entel·K. -D. Schotte
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Abstract

We develop an efficient method to calculate the third-order corrections to the self-energy of the hole-doped two-dimensional Hubbard model in space-time representation. Using the Dyson equation we evaluate the renormalized spectral function in various parts of the Brillouin zone and find significant modifications with respect to the second-order theory even for rather small values of the coupling constant U. The spectral function becomes unphysical for $ U \simeq W $, where W is the half-width of the conduction band. Close to the Fermi surface and for U<W, the single-particle spectral weight is reduced in a finite energy interval around the Fermi energy. The increase of U opens a gap between the occupied and unoccupied parts of the spectral function.

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V. Zlatic, B. Horvatic, B. Dolicki, S. Grabowski, P. Entel, K. -D. Schotte. 2000-10-20. Perturbation expansion for 2-D Hubbard model. https://doi.org/10.1103/physrevb.63.035104

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