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arXiv 1906.04081cond-mat.str-el
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强关联电子:解析平均场论与两粒子自洽

Strongly correlated electrons: Analytic mean-field theories with two-particle self-consistency

Václav Janiš, Peter Zalom, Vladislav Pokorný, Antonín Klíč

摘要:

两粒子自洽性很少是平均场论的一部分。然而,这对于避免虚假的临界跃迁和非物理行为是必不可少的。我们提出了一个一般的计划,用于构造解析可控近似的自洽方程的两粒子顶点的基础上的镶板方程。我们详细解释了如何减少全套的拼花方程不错过量子临界强耦合。我们进一步介绍了一个解耦的卷积的动力学变量的Bethe-Salpeter方程,使它们解析可解。我们将自能与两粒子的顶点联系起来,满足沃德恒等式和Schwinger-Dyson方程。我们讨论的作用,使近似可靠的输入参数的整个频谱的单粒子自洽性。我们证明了最简单的静态近似,我们适用于近藤行为的单杂质安德森模型的一般建设。

英文摘要:

A two-particle self-consistency is rarely part of mean-field theories. It is, however, essential for avoiding spurious critical transitions and unphysical behavior. We present a general scheme for constructing analytically controllable approximations with self-consistent equations for the two-particle vertices based on the parquet equations. We explain in detail how to reduce the full set of parquet equations not to miss quantum criticality in strong coupling. We further introduce a decoupling of convolutions of the dynamical variables in the Bethe-Salpeter equations to make them analytically solvable. We connect the self-energy with the two-particle vertices to satisfy the Ward identity and the Schwinger-Dyson equation. We discuss the role of the one-particle self-consistency in making the approximations reliable in the whole spectrum of the input parameters. We demonstrate the general construction on the simplest static approximation that we apply to the Kondo behavior of the single-impurity Anderson model.

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