Generalization of the iterative perturbation theory and metal-insulator   transition in multi-orbital Hubbard bands
  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. 
Takeo Fujiwara, Susumu Yamamoto, and Yasushi Ishii