对偶费米子方法中六点单粒子可约局域相互作用的影响
The effect of six-point one-particle reducible local interactions in the dual fermion approach
摘要：
我们制定的双费米子方法强关联电子系统的晶格和双有效相互作用，通过使用协变分裂公式。这使我们能够考虑六点单粒子可约相互作用的影响，这通常被忽略的对偶费米子方法。我们表明，考虑一个粒子约六点（以及更高的顺序）顶点是至关重要的图形的一致性，这种方法。特别是，对偶和晶格自能之间的关系，在对偶费米子的方法，推导出隐含的帐户的影响的图表，包含6点和更高阶的本地一个粒子可约顶点，并应谨慎应用，如果这些顶点被忽略。除此之外，自能反馈的处理也被修改为6点和更高阶的顶点;这些顶点对于解释晶格自能的一些非局部校正也很重要，这些非局部校正在局部4点顶点中具有相同的阶数，正如该方法中通常考虑的图。这些观察启发了6点和更高阶的顶点在对偶费米子方法的重要性，并呼吁发展新的计划的治疗非本地的波动，这是基于一个粒子的不可约量。
英文摘要：
We formulate the dual fermion approach to strongly correlated electronic systems in terms of the lattice and dual effective interactions, obtained by using the covariation splitting formula. This allows us to consider the effect of six-point one-particle reducible interactions, which are usually neglected by the dual fermion approach. We show that the consideration of one-particle reducible six-point (as well as higher order) vertices is crucially important for the diagrammatic consistency of this approach. In particular, the relation between the dual and lattice self-energy, derived in the dual fermion approach, implicitly accounts for the effect of the diagrams, containing 6-point and higher order local one-particle reducible vertices, and should be applied with caution, if these vertices are neglected. Apart from that, the treatment of the self-energy feedback is also modified by 6-point and higher order vertices; these vertices are also important to account for some non-local corrections to the lattice self-energy, which have the same order in the local 4-point vertices, as the diagrams usually considered in the approach. These observations enlighten an importance of 6-point and higher order vertices in the dual fermion approach, and call for development of new schemes of treatment of non-local fluctuations, which are based on one-particle irreducible quantities.
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