Density-matrix renormalisation group approach to quantum impurity problems

TL;DR

This paper introduces a dynamic density-matrix renormalisation group method to accurately compute spectral properties of quantum impurity problems across all frequencies and coupling regimes, including high-energy features.

Contribution

The paper presents a novel DMRG-based approach for spectral analysis of quantum impurity models, capable of resolving sharp features and high-energy satellites.

Findings

Accurately computes impurity spectral density across all frequencies.

Successfully resolves high-energy Hubbard satellites.

Addresses discretisation and spectral resolution challenges.

Abstract

A dynamic density-matrix renormalisation group approach to the spectral properties of quantum impurity problems is presented. The method is demonstrated on the spectral density of the flat-band symmetric single-impurity Anderson model. We show that this approach provides the impurity spectral density for all frequencies and coupling strengths. In particular, Hubbard satellites at high energy can be obtained with a good resolution. The main difficulties are the necessary discretisation of the host band hybridised with the impurity and the resolution of sharp spectral features such as the Abrikosov-Suhl resonance.