SELF-CONSISTENT NUMERICAL-CALCULATIONS FOR NESTED FERMI LIQUIDS

We have carried out propagator-renormalized numerical calculations for the self energy of the 2D Hubbard model generated self-consistently from the second-order skeleton diagram. We use lattices as large as 128 x 128 with 1024 Matsubara frequencies in order to obtain the the self energy at temperatures down to 0.002 times the bandwidth. Our results at and near half filling show marginal Fermi liquid behavior; for U approximately t the frequency dependence of the self energy is similar to that expected from the nested Fermi liquid theory of Virosztek and Ruvalds, but contrary to their model, the momentum dependence near the Fermi surface is strong. We also calculate the temperature dependence of the thermodynamic potential using the functional of Luttinger and Ward, and find significant departures from the T2 dependence expected for a normal Fermi liquid. For n less-than-or-equal-to 0.89, we see normal Fermi liquid behavior for temperatures below 1.5% of the bandwidth.