Generalized Wilson Chain for solving multichannel quantum impurity problems

TL;DR

This paper introduces a generalized Wilson Chain method that enhances the Numerical Renormalization Group technique, enabling efficient analysis of complex multichannel quantum impurity problems and revealing new physical phenomena.

Contribution

A simple generalization of the Wilson Chain that reduces computational costs for multichannel impurity problems, expanding the scope of solvable models.

Findings

Calculated the t-matrix for the three-channel Kondo model at T=0.

Identified universal crossovers near non-Fermi liquid critical points.

Explored a non-integrable three-impurity, three-band system revealing a rich phase diagram.

Abstract

The Numerical Renormalization Group is used to solve quantum impurity problems, which describe magnetic impurities in metals, nanodevices, and correlated materials within DMFT. Here we present a simple generalization of the Wilson Chain, which improves the scaling of computational cost with the number of channels/bands, bringing new problems within reach. The method is applied to calculate the t-matrix of the three-channel Kondo model at T=0, which shows universal crossovers near non-Fermi liquid critical points. A non-integrable three-impurity problem with three bands is also studied, revealing a rich phase diagram and novel screening/overscreening mechanisms.