Evolution of single-particle green functions with correlation in the hubbard model at half-filling: sum rules for the spectral density

• Published in: Physica. B, Condensed matter Condensed matter, 1999, Vol.259, p.773-774
• Main Authors: Rodrı́guez-Núñez, J.J, Schafroth, S, Beck, H
• Format: Article
• Language: English
• Subjects: Hubbard model; Marginal Fermi liquid; Metal–insulator transition
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(98)00940-5

For the U/ t>0 case we have proposed a self-energy with lifetime effects generalizing a previous calculation (Rodrı́guez-Núñez and de Menezes (Physica A, 257 (1998) 501). Our ansatz induces our system to be a Marginal Fermi liquid for small values of the interaction. We have evaluated the three self-energy parameters using the moment approach of Nolting (Z. Physik, 255 (1972) 25) at half-filling for different values of coupling, in the paramagnetic phase. We find: (1) the density of states shows a gap for U/ W≈1. (2) the different single-particle dynamical properties evolve with interaction from almost peak structures for weak coupling to broad structures well into the insulating phase (MMIT); and (3) for intermediate values of interaction it is still possible to define the Fermi surface. However, this becomes impossible for values of interaction close to the Mott metal–insulator transition.