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Conserving approximations for the attractive Holstein and Hubbard models

J. K. Freericks
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Abstract

Conserving approximations are applied to the attractive Holstein and Hubbard models (on an infinite-dimensional hypercubic lattice). All effects of nonconstant density of states and vertex corrections are taken into account in the weak-coupling regime. Infinite summation of certain classes of diagrams turns out to be a quantitatively less accurate approximation than truncation of the conserving approximations to a finite order, but the infinite summation approximations do show the correct qualitative behavior of generating a peak in the transition temperature as the interaction strength increases.

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J. K. Freericks. 1994-02-06. Conserving approximations for the attractive Holstein and Hubbard models. https://doi.org/10.1103/physrevb.50.403

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