  We have addressed the role of electronic correlations in different kind of
band insulators by using two orbital Hubbard model within dynamical mean-field
theory (DMFT). We have derived exact results for a single-particle spectral
function at Fermi level within DMFT. Our numerical results calculated using
impurity solvers namely, hybridization expansion continuous-time quantum
Monte-Carlo (HY-CTQMC) and multi-orbital iterative perturbation theory (MO-IPT)
corroborated with our predicted analytical results.
