Single-particle excitation in one-dimensional extended Hubbard model

Using the numerically exact diagonalization method, we investigate the single-particle excitation spectrum A(k, w) in one-dimensional electron systems. First we perform the calculation for the Hubbard model and characterize the excited states appeared in A(k, w) by quantum numbers of the Bethe ansatz solution. Next we calculate A(k, w) for the extended Hubbard model i.e., the Hubbard model with the nearest-neighbor Coulomb repulsion V. It is found that the energy region where the spin-charge separation is clearly observed becomes smaller than for the Hubbard model because of incoherent excitations caused by V.