In this paper, by using the level spectroscopy method and bosonization theory, we discuss the evolution of the bond-order-wave （BOW） phase in a one-dimensional half-filled extended Hubbard model wlth the on-site Cou...In this paper, by using the level spectroscopy method and bosonization theory, we discuss the evolution of the bond-order-wave （BOW） phase in a one-dimensional half-filled extended Hubbard model wlth the on-site Coulomb repulsion U as well as the inter-site Coulomb repulsion V and antiferromagnetic exchange J. After clarifying the generic phase diagrams in three limiting cases with one of the parameters being fixed at zero individually, we find that the BOW phase in the U-V phase diagram is initially enlarged as J increases from zero but is eventually suppressed as J increases further in the strong-coupling regime. A three-dimensional phase diagram is suggested where the BOW phase exists in an extended region separated from the spin-density-wave and charge-density-wave phases.展开更多
By using the density matrix renormalization group technique, the phase diagram of the half-tilting extended Hubbard model is investigated. The conventional order parameter, the two-site entanglement entropy, and the b...By using the density matrix renormalization group technique, the phase diagram of the half-tilting extended Hubbard model is investigated. The conventional order parameter, the two-site entanglement entropy, and the block- block entanglement entropy are analyzed in detail. According to the numerical results, in the weak coupling region, an intermediate bond-order-wave （BOW） phase is shown to exist indeed between the charge-density-wave （CDW） and the spin-density-wave （SDW） phases. The critical phase transition points are determined by the singularity of the first order derivative of two-site entanglement entropy. In strong coupling region, a direct phase transition occurs from SDW phase to CDW phase, and shows discontinuous （first order） character accompanied with energy level crossing. The numerical results support the phase diagram proposed previously by some authors Sengupta et al., （2002）; Sandvik et al., （2004）; Zhang, （2004）. Therefore, the quantum entanglement is a sensitive tool to describe quantum phase transitions in strongly correlated electron systems.展开更多
基金The project supported in part by National Natural Science Foundation of China and the Natural Science Foundation of Zhejiang Province of China. We acknowledge useful discussions with X. Feng, T. Xiang, and Y. Yu.
文摘In this paper, by using the level spectroscopy method and bosonization theory, we discuss the evolution of the bond-order-wave （BOW） phase in a one-dimensional half-filled extended Hubbard model wlth the on-site Coulomb repulsion U as well as the inter-site Coulomb repulsion V and antiferromagnetic exchange J. After clarifying the generic phase diagrams in three limiting cases with one of the parameters being fixed at zero individually, we find that the BOW phase in the U-V phase diagram is initially enlarged as J increases from zero but is eventually suppressed as J increases further in the strong-coupling regime. A three-dimensional phase diagram is suggested where the BOW phase exists in an extended region separated from the spin-density-wave and charge-density-wave phases.
基金Supported by the National Natural Science Foundation of China under Grant No.11047160the National Basic Research Program of China under Grant No.2009CB939901the Foundation of Tianjin Polytechnic University under Grant No.029289
文摘By using the density matrix renormalization group technique, the phase diagram of the half-tilting extended Hubbard model is investigated. The conventional order parameter, the two-site entanglement entropy, and the block- block entanglement entropy are analyzed in detail. According to the numerical results, in the weak coupling region, an intermediate bond-order-wave （BOW） phase is shown to exist indeed between the charge-density-wave （CDW） and the spin-density-wave （SDW） phases. The critical phase transition points are determined by the singularity of the first order derivative of two-site entanglement entropy. In strong coupling region, a direct phase transition occurs from SDW phase to CDW phase, and shows discontinuous （first order） character accompanied with energy level crossing. The numerical results support the phase diagram proposed previously by some authors Sengupta et al., （2002）; Sandvik et al., （2004）; Zhang, （2004）. Therefore, the quantum entanglement is a sensitive tool to describe quantum phase transitions in strongly correlated electron systems.
