The dual fermion (DF) method allows for calculating corrections due to non-local correlations relative to an effective impurity model. Choosing the impurity as that of a dynamical mean field theory (DMFT) solution at self-consistency is popular, and the corrections from dual fermion theory are physically meaningful. We investigate the effect of choosing the impurity instead in a self-consistent manner and find for the two dimensional Hubbard model an exponentially increase of the correlation length and susceptibility at low temperatures. There are pronounced differences for the two self-consistency schemes that are discussed in the literature; the self-consistent DF solution can even be more metallic than the DMFT solution.
@article{arxiv.1805.10996,
title = {Impact of self-consistency in dual fermion calculations},
author = {Tin Ribic and Patrik Gunacker and Karsten Held},
journal= {arXiv preprint arXiv:1805.10996},
year = {2018}
}