Algorithm for computing perturbation series of dynamical mean field theory

TL;DR

This paper introduces a diagrammatic technique to compute the perturbation series in dynamical mean field theory, providing an alternative to traditional impurity solvers and applicable in various formalisms and out-of-equilibrium scenarios.

Contribution

It presents a novel diagrammatic approach for perturbation series calculation in DMFT that avoids multiple resummations and is versatile across different formalisms and conditions.

Findings

Successfully applied to the half-filled Hubbard model on the Bethe lattice

Demonstrated compatibility with real-time Quantum Quasi-Monte Carlo methods

Provides an efficient alternative to existing impurity solvers

Abstract

We show how to use diagrammatic techniques to compute the weak-coupling perturbation series of the self-consistent solution to a Dynamical Mean Field Theory (DMFT) problem. This approach constitutes an alternative to using diagrammatic techniques directly as an impurity solver. It allows one to bypass the need of multiple perturbative series resummations within the DMFT self-consistency loop. It can be applied at or out of equilibrium, with any diagrammatic formalism, such as real times, imaginary times, or Matsubara frequencies formalisms. As a proof of principle, we illustrate our method with the half-filled Hubbard model on the Bethe lattice in the DMFT approximation, using Quantum Quasi-Monte Carlo (QQMC) to obtain the impurity perturbation series on the real time axis.