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arXiv 0904.4673cond-mat.str-el
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半满扩展哈伯德模型的phase diagram的量子信息分析

Quantum information analysis of the phase diagram of the half-filled extended Hubbard model

C. Mund, O. Legeza, R. M. Noack

摘要:

利用密度矩阵重整化群中的量子信息熵研究了半满一维扩展Hubbard模型的相图。在最近邻排斥大、在位排斥小的情况下,存在电荷密度波相;在最近邻排斥小、在位排斥大的情况下,存在自旋密度波相。在中间库仑相互作用强度,我们发现这两个阶段之间的键序相的一个额外的狭窄区域。的相变线的电荷密度波相位的变化,从一阶在强耦合到二阶的参数制度,其中所有三个阶段都存在。我们提出的证据表明,额外的相变线之间的自旋密度波和键序阶段是无限的顺序。虽然这些结果与最近的数值计算工作,我们的研究提供了一个独立的,公正的手段,确定的相边界,通过使用量子信息分析,产生值的位置的一些相边界,不同于以前发现的,并提供了深入了解数值方法在确定相边界的局限性,特别是那些无限阶过渡。

英文摘要:

We examine the phase diagram of the half-filled one-dimensional extended Hubbard model using quantum information entropies within the density-matrix renormalization group. It is well known that there is a charge-density-wave phase at large nearest-neighbor and small on-site Coloumb repulsion and a spin-density-wave at small nearest-neighbor and large on-site Coloumb repulsion. At intermediate Coulomb interaction strength, we find an additional narrow region of a bond-order phase between these two phases. The phase transition line for the transition out of the charge-density-wave phase changes from first-order at strong coupling to second-order in a parameter regime where all three phases are present. We present evidence that the additional phase-transition line between the spin-density-wave and bond-order phases is infinite order. While these results are in agreement with recent numerical work, our study provides an independent, unbiased means of determining the phase boundaries by using quantum information analysis, yields values for the location of some of the phase boundaries that differ from those previously found, and provides insight into the limitations of numerical methods in determining phase boundaries, especially those of infinite-order transitions.

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