Physical review. B, Condensed matter
Effect of the intersite Coulomb interaction in the extended Hubbard model
Mei-Rong Li, Yong-Jun Wang, Chang-De Gong
Abstract
Starting from the large-U Hubbard model combining the intersite Coulomb interaction V, we investigate the competition, on a square lattice, between the d-wave resonating-valence-bond (RVB) state and the staggered-flux-phases (SFP) state on the basis of F. C. Zhang's earlier work [Phys. Rev. Lett. 64, 974 (1990)]. We find that a very small V (0.1U) may help stabilize the SFP state by effectively suppressing the d-wave pairing amplitude and enhance the particle-hole correlation. We show in the phase diagram of V-\ensuremath{\delta} (the doping concentration) the critical curve of ${\mathit{V}}_{\mathit{c}}$(\ensuremath{\delta}) below which the RVB state is energetically favored while beyond this point a mixed state of SFP and RVB occurs, which has the lowest energy. We also find that the pure SFP state is not the most stable state in the whole V region.