Band Insulators and Hubbard interactions

We investigate the theoretical models which are band insulators in the abscence of interaction and evolve into Mott insulators under strong mutual repulsive interaction. We use the cellular dynamical mean-field theory to study the nature of the interaction-driven transitions in the systems. In various systems we compute the renormalized band gap which is defined by the self-energy corrected band gap and show that it is a convenient measure to characterize band insulating phases in such systems; the spectral gap is fully explained by the renormalized band gap when the systems remain in the band insulating phase. Finally we discuss interesting transition behavior from a band insulator to a Mott insulator.