title: Phase diagram of the one-dimensional extended Hubbard model at half filling.
abstract: We reexamine the ground-state phase diagram of the one-dimensional half-filled Hubbard model with on-site and nearest-neighbor repulsive interactions. We calculate second-order corrections to coupling constants in the weak-coupling renormalization-group approach ( g-ology) to show that the bond-charge-density-wave (BCDW) phase exists for weak couplings in between the charge-density-wave (CDW) and spin-density-wave (SDW) phases. We find that the umklapp scattering of parallel-spin electrons destabilizes the BCDW state and gives rise to a bicritical point where the CDW-BCDW and SDW-BCDW continuous-transition lines merge into the CDW-SDW first-order transition line.
authors.affiliation: Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tsuchiizu
authors.forename: A
authors.initials: A
authors.lastname: Furusaki