Dynamical Screening Effect on Local Two-Particle Vertex Functions

TL;DR

This paper investigates how the frequency-dependent dynamical screening of Coulomb interactions significantly alters local two-particle Green's and vertex functions within dynamical mean-field theory, impacting the understanding of correlated materials.

Contribution

It demonstrates that dynamical screening strongly modifies local two-particle functions, highlighting the need to reconsider previous models that neglected this effect.

Findings

Local two-particle Green's functions are significantly affected by dynamical screening.

Vertex functions show substantial modifications due to frequency-dependent interactions.

Reevaluation of prior results is necessary when including dynamical screening effects.

Abstract

In principle, the electronic Coulomb interaction among the correlated orbitals is frequency-dependent. Though it is generally believed that the dynamically screened interaction may play a crucial role in understanding the subtle electronic structures of strongly correlated materials, hitherto we know very little about it. In the Letter, we demonstrate that within the framework of single-site dynamical mean-field theory the local two-particle Green's functions $\chi$ and vertex functions $\Gamma$ are strongly modified by the dynamically screened interaction. Since both $\chi$ and $\Gamma$ represent the main ingredients to compute momentum-resolved response functions and to treat non-local spatial correlations by means of diagrammatic extensions of dynamical mean-field theory, it is urgent to reexamine previous results by taking the dynamical screening effect into account. The modifications should be very considerable.