Double Counting in LDA+DMFT - The Example of NiO

TL;DR

This paper investigates the double counting problem in LDA+DMFT calculations for NiO, analyzing how different correction choices affect the spectral properties and proposing a scheme for insulating systems.

Contribution

It provides a systematic study of double counting effects in NiO and introduces a new scheme for determining the correction in insulating materials.

Findings

Different double counting methods can alter NiO's spectral state from Mott insulator to metal.

Explicit treatment of double counting as a parameter reveals its significant impact.

Proposes a physically motivated scheme for fixing double counting in insulators.

Abstract

An intrinsic issue of the LDA+DMFT approach is the so called double counting of interaction terms. How to choose the double-counting potential in a manner that is both physically sound and consistent is unknown. We have conducted an extensive study of the charge transfer system NiO in the LDA+DMFT framework using quantum Monte Carlo and exact diagonalization as impurity solvers. By explicitly treating the double-counting correction as an adjustable parameter we systematically investigated the effects of different choices for the double counting on the spectral function. Different methods for fixing the double counting can drive the result from Mott insulating to almost metallic. We propose a reasonable scheme for the determination of double-counting corrections for insulating systems.