ELECTRONIC-SPECTRUM OF THE D-DIMENSIONAL HUBBARD-MODEL

The electronic spectrum of the d-dimensional tight-binding Hubbard Mod el is examined near the point of half filled bands, The electronic spe ctrum is calculated by treating the longitudinal and transverse spin f luctuations in the random phase approximation. For zero doping, a comm ensurate anti-ferromagnetic structure is found to be stable. The elect ronic structure shows the opening up of a gap at the Fermi-level. As t he system is doped, the anti-ferromagnetic structure immediately becom es unstable to an incommensurate spiral spin density wave phase. Howev er, the existence of small nearest-neighbor hopping matrix element sta bilizes the Neel stale over the range of dopings close to half filling , as this disturbs the perfect nesting of the Fermi-surface.