Model for a strongly correlated insulator: FeSi.

Prompted by suggestions that FeSi may be a strongly correlated insulator, somewhat analogous to the Kondo insulators, we study the properties of a two-band Hubbard model Hamiltonian in the infinite-dimensional limit. By a calculation of the one-particle self-energy using self-consistent second-order perturbation theory we are able to calculate the temperature dependence of the magnetic susceptibility and of angle-resolved photoemission spectra. The results are in fair agreement with experimental data on FeSi.