Correlation effects on the Fermi surface of the two-dimensional Hubbard model Original Research Article

Effects of electron correlation on the Fermi surface (FS) is investigated for the two-dimensional Hubbard model by the quantum Monte Carlo method. At first, an infinitesimal doping from the half-filling is focused on and the momentum-dependent charge susceptibility κ(k)=dn(k)/dμ is calculated at a finite temperature. At the temperature T∼t2/U, it shows peak structure at (±π/2,±π/2) on the FS (line). It is consistent with the mean-field prediction of the d-wave pairing state or the staggered flux state. This momentum-dependent structure disappears at the high temperature T≈U. After summarizing the results of the half-filling case, we also discuss the effects of the doping on the momentum-dependent charge susceptibility. The anisotropic structure at half-filling fades out with sufficient doping.