Third-order perturbation theory for 2-D Hubbard model. Physical Review B (2001) (CROSBI ID 103782)
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Podaci o odgovornosti
Zlatić, Veljko ; Horvatić, Berislav ; Dolički, Branimir ; Grabowski, Stefan ; Entel, Peter
engleski
Third-order perturbation theory for 2-D Hubbard model. Physical Review B (2001)
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~=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.
Hubbard model; spectral properties
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