  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 $(0,\pi),(\pi,0)$ points in the Brillouin zone, in
accordance with experimental data for high-temperature superconducting
compounds.
