From cluster to solid - the variational cluster approximation applied to NiO

TL;DR

This paper applies the variational cluster approximation to NiO, using exact diagonalization of NiO6-clusters to compute spectral functions, achieving good agreement with experimental data.

Contribution

It introduces a novel application of the variational cluster approximation to NiO, utilizing cluster self energies and the Luttinger-Ward functional for accurate spectral calculations.

Findings

Good agreement with experimental spectral data for NiO

Effective use of NiO6-clusters for variational calculations

Demonstrates the viability of the method for strongly correlated materials

Abstract

The variational cluster approximation is applied to the calculation of the single particle spectral function of NiO. Trial self energies and the numerical value of the Luttinger-Ward functional are obtained by exact diagonalization of NiO6-clusters and the single particle parameters of the clusters serve as variational parameters to obtain a stationary point of the grand potential of the lattice system. Good agreement with experiment is obtained.