Spectral weight function for the half-filled Hubbard model: a singular value decomposition approach

TL;DR

This paper applies singular value decomposition to Quantum Monte Carlo data to reconstruct the spectral weight function of the half-filled Hubbard model, revealing a persistent two-band structure consistent with experimental observations.

Contribution

It introduces a SVD-based method to analyze spectral functions in the Hubbard model, demonstrating the persistence of a two-band structure at large lattice sizes.

Findings

Two-band structure persists beyond the spin-spin correlation length

Bands are flat near specific Brillouin zone points

Results align with experimental data for high-temperature superconductors

Abstract

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.