Exact diagonalization of a one-dimensional Hubbard model at density rho=0.4: Effects of Coulomb repulsions and distant transfer

Abstract

An extended Hubbard model that includes not only on-site but also intersite Coulomb repulsion and distant transfer is numerically investigated using the exact Lanczos diagonalization method for finite-size systems up to L=20 sites. The aim is to study the charge order and unconditional dimerization of a chain at density rho=0.4. From the analysis of the spin and charge correlation functions, we deduce the formation of a dimer insulating state which is a Wigner lattice-type charge ordered state. The next-nearest-neighbor hopping t(2) enhances the intradimer correlations and weakens the interdimer correlations. Implications for the CuO2 chains in Sr14Cu24O41 are discussed.