Dynamic mean-field theory of the ionic Hubbard model

We study the ionic Hubbard model in the infinite dimensions in the framework of dynamical mean-field theory. Exact diagonalization is used to obtain the impurity Green's function to satisfy the self-consistant equation. We obtain a phase diagram in the parameter space of local ionic potential strength, $\Delta$ and local repulsive energy, $U$ exhibiting three phases: Mott insulator, metal, band insulator. Analyzing the spectral density, we compare our results with those of iterative perturbation theory and quantum Monte Carlo study in two dimensions.