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arXiv 0812.0234cond-mat.str-elcond-mat.other
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半满扩展哈伯德模型键级波(BOW)相位的调谐

Tuning the bond order wave (BOW) phase of half-filled extended Hubbard models

Manoranjan Kumar, S. Ramasesha, Z. G. Soos

摘要:

对一维半满扩展Hubbard模型(EHM)的量子相图的理论和计算研究表明,在临界点$U < U^*$和最近邻相互作用$V_c \approx U/2$附近的电荷密度波(CDW)相的边界处,存在一个窄的键序波(BOW)相,其磁隙为有限的$E_m$.保留EHM对称性的具有更多扩展相互作用的势被示出具有更高的$U^*$和更宽的BOW相位的较少合作的CDW转变。利用密度矩阵重整化群(DMRG)直接得到$E_m$作为单重态-三重态能隙,有限$E_m$标记BOW边界$V_s(U)$ . BOW/CDW边界$V_c(U)$是从精确的有限尺寸计算得到的,与以前的EHM测定一致。基于$U < U^*$在$V_c(U)$上的金属点,动能或键级提供了一种方便的$U^*$新估计。调整的BOW阶段的半填充哈伯德模型与不同的intersite电位表明,基态与大的电荷波动和磁挫折。提出了库仑作用下BOW相物理实现的可能性。

英文摘要:

Theoretical and computational studies of the quantum phase diagram of the one-dimensional half-filled extended Hubbard model (EHM) indicate a narrow bond order wave (BOW) phase with finite magnetic gap $E_m$ for on-site repulsion $U < U^*$, the critical point, and nearest neighbor interaction $V_c \approx U/2$ near the boundary of the charge density wave (CDW) phase. Potentials with more extended interactions that retain the EHM symmetry are shown to have a less cooperative CDW transition with higher $U^*$ and wider BOW phase. Density matrix renormalization group (DMRG) is used to obtain $E_m$ directly as the singlet-triplet gap, with finite $E_m$ marking the BOW boundary $V_s(U)$. The BOW/CDW boundary $V_c(U)$ is obtained from exact finite-size calculations that are consistent with previous EHM determinations. The kinetic energy or bond order provides a convenient new estimate of $U^*$ based on a metallic point at $V_c(U)$ for $U < U^*$. Tuning the BOW phase of half-filled Hubbard models with different intersite potentials indicates a ground state with large charge fluctuations and magnetic frustration. The possibility of physical realizations of a BOW phase is raised for Coulomb interactions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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