Single-particle spectra of charge-transfer insulators by cluster perturbation theory: The correlated band structure of NiO

Abstract

We propose a many-body method for band-structure calculations in strongly correlated electron systems and apply it to NiO. The method may be viewed as a translationally invariant version of the cluster method of Fujimori and Minami. Thereby the Coulomb interaction within the d-shells is treated by exact diagonalization and the d-shells then are coupled to a solid by an extension of the cluster perturbation theory due to Senechal et al. The method is computationally no more demanding than a conventional band structure calculation and for NiO we find good agreement between the calculated single particle spectral function and the experimentally measured band structure.

Correlated band structure of NiO, CoO, and MnO by variational cluster approximation

“…Separated from this group of dispersive bands there is then a region with many almost dispersionless bands with relatively low spectral weight. This overall structure can be understood by considering the spectral representation of the self energy (19) and the equation for the poles of the Green's function where we have considered the single band case for simplicity. Since Re Σ(ω) takes any value between ∞ and −∞ in between two successive poles ζ ν and ζ ν+1 there is one band in between any two successive poles of the self energy.…”

“…This is also in contradition to LDA calculations which predicts band widths of around 2eV for the TM3d-derived bands. Starting with the work of Hubbard [11] a variety of theoretical methods have been invented to deal with this problem [12,13,14,15,16,17,18,19,20,21,22]. Major progress towards a quantitative description of 3d TM oxides has been made by the cluster method initiated by Fujimori and Minami [23,24,25,26,27] This takes the opposite point of view as compared to band theory, namely to abandon translational invariance and instead treat exactly -by means of atomic multiplet theory [28,29] -the Coulomb interaction in the 3d-shell of a TM-ion in an octahedral 'cage' of nearest-neighbor oxygen atoms.…”

Challenges from experiment: electronic structure of NiO

“…These include several types of GW calculations [26,27], LDA+DMFT [28][29][30][31][32][33][34][35][36], VCA (variational cluster approximation) [37][38][39][40] as well as calculations of the relevant screened interactions [41]. Focussing on the LDA+DMFT studies, we notice that they differ in the impurity solver utilized and in the implementation of the double counting correction.…”

Charge transfer and dd excitations in transition metal oxides

“…[5][6][7][8]). However, many of recent reports adopting advanced theory show that correlated d electrons generally split into three bands, i.e., UHB, LHB, plus an additional band that is well hybridized with the p bands between the UHB and the LHB [9][10][11][12][13][14]. This third band has been argued to a e-mail: hiraoka@spring8.or.jp b Present address: Japan Atomic Energy Agency, (JAEA/ SPring-8), 1-1-1, Kouto, Sayo, 6795198 Hyogo, Japan c Present address: National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, 11973 NY, USA correspond to a Zhang-Rice singlet in cuprates, implying that the Mott gap is given by the transition from this Zhang-Rice band to the UHB.…”