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arXiv 0704.0249cond-mat.str-el
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非微扰守恒近似与Luttinger求和规则

Non-perturbative conserving approximations and Luttinger's sum rule

Jutta Ortloff, Matthias Balzer, Michael Potthoff

摘要:

弱耦合守恒近似可以通过截断Luttinger-Ward泛函来构造,并且是众所周知的物理相容方法,其尊重宏观守恒定律以及零温度下的某些求和规则。这些属性也可以显示为变分近似的自能泛函理论的框架内产生的,没有截断的图系列。Luttinger的求和规则是一个例外。我们分析的条件下,在非微扰保守近似的总和规则。数值例子给出了一个简单的,但非平凡的动力学两个网站的近似。本文讨论了有限Hubbard团簇求和规则的有效性以及动力学平均场论对团簇扩展的影响。

英文摘要:

Weak-coupling conserving approximations can be constructed by truncations of the Luttinger-Ward functional and are well known as thermodynamically consistent approaches which respect macroscopic conservation laws as well as certain sum rules at zero temperature. These properties can also be shown for variational approximations that are generated within the framework of the self-energy-functional theory without a truncation of the diagram series. Luttinger's sum rule represents an exception. We analyze the conditions under which the sum rule holds within a non-perturbative conserving approximation. Numerical examples are given for a simple but non-trivial dynamical two-site approximation. The validity of the sum rule for finite Hubbard clusters and the consequences for cluster extensions of the dynamical mean-field theory are discussed.

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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