Physical review. B, Condensed matter
Momentum-distribution critical exponents for the one-dimensional large-UHubbard model in the thermodynamic limit
Shaojin Qin, Lu Yu
Abstract
The critical exponents of the momentum distribution near ${\mathit{k}}_{\mathit{F}}$, 3${\mathit{k}}_{\mathit{F}}$, and 5${\mathit{k}}_{\mathit{F}}$ are studied numerically for the one-dimensional U\ensuremath{\rightarrow}\ensuremath{\infty} Hubbard model, using finite-size systems and extrapolating them to the thermodynamic limit. Results at ${\mathit{k}}_{\mathit{F}}$ agree with earlier calculations, while at 3${\mathit{k}}_{\mathit{F}}$, exponents less than 1 are obtained for finite-size systems with extrapolation to 1 (regular behavior) in the thermodynamic limit, in contrast to the earlier analytic prediction of 9/8. The distribution is regular at 5${\mathit{k}}_{\mathit{F}}$ even for finite systems. The singularity near 3${\mathit{k}}_{\mathit{F}}$ is interpreted as due to low-energy excitations near 3${\mathit{k}}_{\mathit{F}}$ in finite systems. \textcopyright{} 1996 The American Physical Society.