Parquet dual fermion approach for the Falicov-Kimball model

TL;DR

This paper investigates the Falicov-Kimball model using a dual fermion approach, revealing that weak localization effects depend on the approximation method and highlighting the dominant contributions to optical conductivity.

Contribution

It demonstrates that the parquet dual fermion approach suppresses weak localization effects seen in simpler approximations, clarifying the main channels affecting optical conductivity.

Findings

Weak localization appears only in the pp-ladder approximation.

In the full parquet approach, pp-contributions are suppressed by ph-reducible diagrams.

The pht-channel dominates the optical conductivity contributions.

Abstract

In the Falicov-Kimball model, a model for (annealed) disorder, we expect weak localization corrections to the optical conductivity. However, we get such weak localization effects only when employing a pp-ladder approximation in the dual fermion approach. In the full parquet approach these pp-contributions are suppressed by ph-reducible diagrams. For the optical conductivity, we find that the pht-channel yields the main contribution, even in the region where weak localization in the pp-ladder was indicated.