BETHE-ANSATZ WAVE-FUNCTION, MOMENTUM DISTRIBUTION, AND SPIN CORRELATION IN THE ONE-DIMENSIONAL STRONGLY CORRELATED HUBBARD-MODEL

The momentum distribution function n(k) and spin-correlation function S(k) are determined for the one-dimensional large-U Hubbard model with various electron densities. The present work is featured with an application of the Bethe-ansatz wave function, which has a simple form in the large-U limit for any electron density. Namely, its charge degrees of freedom are expressed as a Slater determinant of spinless fermions, while its spin degrees of freedom are equivalent to the one-dimensional S=(1/2 Heisenberg model. The singularity of n(k) at k=kF is analyzed from the system size dependence. In addition to the kF singularity, n(k) has a weak singularity at k=3kF; however, no detectable singularity is present at 2kF, which one might expect from the spinless fermion wave function. The singularity of S(k) at 2kF is also examined in detail. It is concluded from the size dependence that, when the system is away from half-filling, the nature of the singularity at 2kF is different from that in the Heisenberg model. The results are compared with the behavior in the weak-correlation regime examined with the perturbation calculation, the prediction of g-ology, and recent Monte Carlo calculations. © 1990 The American Physical Society.