Many-body effects in iron pnictides and chalcogenides -- non-local vs dynamic origin of effective masses

TL;DR

This paper uses the QSGW approximation to study iron-based superconductors, showing it accurately predicts electronic properties and separates non-local and dynamic effects on effective masses, suggesting combined methods improve understanding.

Contribution

The study demonstrates that QSGW effectively captures non-local effects and partially accounts for dynamic renormalizations, providing insights into many-body physics in iron pnictides and chalcogenides.

Findings

QSGW results agree well with experimental Fermi surfaces and density of states.

Non-local and dynamic contributions to effective masses are mostly separable.

QSGW combined with DMFT can capture most many-body effects.

Abstract

We apply the quasi-particle self-consistent GW (QSGW) approximation to some of the iron pnictide and chalcogenide superconductors. We compute Fermi surfaces and density of states, and find excellent agreement with experiment, substantially improving over standard band-structure methods. Analyzing the QSGW self-energy we discuss non-local and dynamic contributions to effective masses. We present evidence that the two contributions are mostly separable, since the quasi-particle weight is found to be essentially independent of momentum. The main effect of non locality is captured by the static but non-local QSGW effective potential. Moreover, these non-local self-energy corrections, absent in e.g. dynamical mean field theory (DMFT), can be relatively large. We show, on the other hand, that QSGW only partially accounts for dynamic renormalizations at low energies. These findings suggest that QSGW combined with DMFT will capture most of the many-body physics in the iron pnictides and chalcogenides.