A real-frequency solver for the Anderson impurity model based on bath optimization and cluster perturbation theory

Manuel Zingl, Martin Nuss, Daniel Bauernfeind, Markus Aichhorn*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Recently solvers for the Anderson impurity model (AIM) working directly on the real-frequency axis have gained much interest. A simple and yet frequently used impurity solver is exact diagonalization (ED), which is based on a discretization of the AIM bath degrees of freedom. Usually, the bath parameters cannot be obtained directly on the real-frequency axis, but have to be determined by a fit procedure on the Matsubara axis. In this work we present an approach where the bath degrees of freedom are first discretized directly on the real-frequency axis using a large number of bath sites (≈50). Then, the bath is optimized by unitary transformations such that it separates into two parts that are weakly coupled. One part contains the impurity site and its interacting Green's functions can be determined with ED. The other (larger) part is a non-interacting system containing all the remaining bath sites. Finally, the Green's function of the full AIM is calculated via coupling these two parts with cluster perturbation theory.

Original languageEnglish
Pages (from-to)254
JournalPhysica B: Condensed Matter
Volume537
Early online date2017
DOIs
Publication statusPublished - 1 May 2018

Keywords

  • Anderson impurity model
  • Bath optimization
  • Cluster perturbation theory
  • Exact diagonalization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cooperations

  • NAWI Graz

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