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arXiv 1204.0672cond-mat.mes-hall
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一维无序晶格中的相互作用费米子:用晶格密度泛函理论探索局域化和输运性质

Interacting fermions in 1D disordered lattices: Exploring localization and transport properties with lattice density-functional theories

V. Vettchinkina, A. Kartsev, D. Karlsson, C. Verdozzi

摘要:

本文研究了与半无限导线接触的无序Hubbard链中一维相互作用费米子的静态和动态行为。链描述通过排斥的安德森-哈伯德哈密顿量,使用静态和时间依赖的晶格密度泛函理论。我们的量子输运系统的动力学行为是通过文献中的积分方案进行的,我们通过递归Lanczos方法对其进行修改,以提高其效率。为了量化由于无序和相互作用的本地化程度,我们适应的定义的逆参与比,以获得一个指标,这是既适合于量子输运几何形状,并可以在密度泛函理论内获得。回顾了晶格密度泛函理论,分析了相干势近似在描述接触链光谱性质方面的优点和局限性,并通过晶格密度泛函理论讨论了相互作用.我们的方法似乎能够捕捉复杂的功能,由于无序和相互作用之间的竞争。具体来说,我们发现一个动态增强的离域在存在一个有限的偏见,和增加的稳态电流引起的粒子间的相互作用。这种行为是证实了随时间变化的密度和参与率的倒数的结果。利用具有相互作用和无序的孤立短链,对含时密度泛函理论和精确结果进行了简要的比较分析,并给出了一般的结论性意见。

英文摘要:

We investigate the static and dynamical behavior of 1D interacting fermions in disordered Hubbard chains, contacted to semi-infinite leads. The chains are described via the repulsive Anderson-Hubbard Hamiltonian, using static and time-dependent lattice density-functional theory. The dynamical behavior of our quantum transport system is performed via an integration scheme available in the literature, which we modify via the recursive Lanczos method, to increase its efficiency. To quantify the degree of localization due to disorder and interactions, we adapt the definition of the inverse participation ratio to obtain an indicator which is both suitable for quantum transport geometries and which can be obtained within density-functional theory. Lattice density functional theories are reviewed and, for contacted chains, we analyze the merits and limits of the coherent-potential approximation in describing the spectral properties, with interactions included via lattice density functional theory. Our approach appears to able to capture complex features due to the competition between disorder and interactions. Specifically, we find a dynamical enhancement of delocalization in presence of a finite bias, and an increase of the steady-state current induced by inter-particle interactions. This behavior is corroborated by results for the time-dependent densities and for the inverse participation ratio. Using short isolated chains with interaction and disorder, a brief comparative analysis between time-dependent density-functional theory and exact results is then given, followed by general conclusive remarks.

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