Generalization of the iterative perturbation theory and metal-insulator transition in multi-orbital Hubbard bands

TL;DR

This paper extends the iterative perturbation theory within dynamical mean field theory to multi-orbital systems, demonstrating how electron correlations induce metal-insulator transitions at specific fillings.

Contribution

The authors generalize the iterative perturbation theory for multi-orbital Hubbard models and analyze the metal-insulator transition at various electron occupations.

Findings

A gap opens at integer fillings indicating an insulator phase.

The method can be integrated with LSDA electronic structure calculations.

Numerical results for doubly degenerate Eg bands show electron ionization and affinity levels.

Abstract

The iterative perturbation theory of the dynamical mean field theory is generalized to arbitrary electron occupation in case of multi-orbital Hubbard bands. We present numerical results of doubly degenerate Eg bands in a simple cubic lattice. The spectrum shows the electron ionization and affinity levels of different electron occupations. For sufficiently large Coulomb integral, a gap opens in the spectrum at integer filling of electrons and the system becomes insulator. The present scheme is easy to combine with the LSDA electronic structure theory.