Superperturbation theory on the real-axis

TL;DR

This paper develops a superperturbation theory-based impurity solver for the Anderson model on the real axis, enabling direct calculation of dynamical properties without analytical continuation, thus improving studies of multiplet effects in solids.

Contribution

It introduces a novel superperturbation approach for the Anderson impurity model on the real axis, bypassing traditional analytical continuation methods.

Findings

Allows direct evaluation of dynamical quantities on the real axis

Applicable to multi-orbital problems in solids

Facilitates studying multiplet effects within dynamical mean field theory

Abstract

In this article we formulate the superperturbation theory for the Anderson impurity model on the real axis. The resulting impurity solver allows to evaluate dynamical quantities without numerical analytical continuation by the maximum entropy method or Pad\'e approximants. This makes the solver well suited to study multiplet effects in solids within the dynamical mean field theory. First examples including multi-orbital problems are discussed.