Abstract
We consider a generalized Hubbard model with on-site interaction U, nearest-neighbor repulsion V, and nearest-neighbor hopping for spin σ, which depends on the sum of particles with opposite spin in the two sites involved. The hopping matrix elements are denoted by ,, for =0,1,2, respectively. For 0<<=, we have determined the regions of parameters for which the ground-state (GS) of the one-dimensional system is a charge-density wave (CDW), a spin-density wave (SDW), or a metal (M), using Hartree-Fock, exact diagonalization of finite chains and quantum Monte Carlo. The results agree qualitatively with the exactly solvable limit of =0. For 0<<=, the GS is a M for sufficiently low values of U and V. In contrast, when +-=0, our results suggest that the GS is either a CDW or a SDW, with the boundary between them lying near the line U=2V.
DOI:https://doi.org/10.1103/PhysRevB.55.1173
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