An alternative functional renormalization group approach to the single impurity Anderson model

TL;DR

This paper introduces a new functional renormalization group method for the single-impurity Anderson model, enabling detailed analysis of spectral properties, conductance, and magnetic susceptibility at finite temperatures, with results comparable to NRG.

Contribution

It proposes an alternative fRG approach starting from a small correlated core, comparing truncations and core choices, and analyzing Kondo physics signatures.

Findings

Accurately computes spectra, conductance, and susceptibility.

Shows good agreement with numerical renormalization group results.

Provides insights into Kondo physics within the fRG framework.

Abstract

We present an alternative functional renormalization group (fRG) approach to the single-impurity Anderson model at finite temperatures. Starting with the exact self-energy and interaction vertex of a small system ('core') containing a correlated site, we switch on the hybridization with a non-interacting bath in the fRG-flow and calculate spectra of the correlated site. Different truncations of the RG-flow-equations and choices of the core are compared and discussed. Furthermore we calculate the linear conductance and the magnetic susceptibility as functions of temperature and interaction strength. The signatures of Kondo physics arising in the flow are compared with numerical renormalization group results.