Spectral Weight Function for the Half-Filled Hubbard Model: A Singular Value Decomposition Approach

The singular value decomposition technique is used to reconstruct the electronic spectral weight function for a half-filled Hubbard model with on-site repulsion $U=4t$ from quantum Monte Carlo data. A two-band structure for the single-particle excitation spectrum is found to persist as the lattice size exceeds the spin-spin correlation length. The observed bands are flat in the vicinity of the $(0,\pi ),(\pi ,0\mathrm{})$ points in the Brillouin zone, in accordance with experimental data for high-temperature superconducting compounds.