Legendre Transformation of the Luttinger-Ward Functional from the Bare Interaction Vertex to the Renormalized One

Takafumi Kita

doi:10.7566/jpsj.91.114002

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arXiv · 2210.08660

Legendre Transformation of the Luttinger-Ward Functional from the Bare Interaction Vertex to the Renormalized One

Takafumi Kita

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Abstract

On the basis of the Luttinger-Ward functional for interacting many-body systems given in terms of full Green's function $G$ and the bare interaction vertex $\Gamma^{(0)}$, we develop a novel Legendre transformation to express the grand thermodynamic potential $\Omega$ as a functional of $G$ and the renormalized interaction vertex $\Gamma$ so that (i) $G$ and $\Gamma$ obey the stationarity conditions $\delta\Omega/\delta G=0$ and $\delta\Omega /\delta\Gamma=0$ and (ii) $\Gamma$ reduces to $\Gamma^{(0)}$ in the weak-coupling limit. The formalism enables us to perform microscopic studies of thermodynamic, single-particle, and two-particle properties in a unified self-consistent conserving framework.

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Takafumi Kita. 2022-10-16. Legendre Transformation of the Luttinger-Ward Functional from the Bare Interaction Vertex to the Renormalized One. https://doi.org/10.7566/jpsj.91.114002

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