Energy spectrum and metal-insulator transition in system with Anderson-Hubbard centers

Energy spectrum of a model of narrow-band metal into which the periodically spaced Anderson-Hubbard centers are introduced has been studied. Hybridization with conduction band results in the indirect exchange interaction which is different from the interactions between localized magnetic moments and strong on-site Coulomb interaction. To study effect of the lattice deformation under the external pressure (or the self-contraction of the lattice) on electrical properties of the system, the phonon term and elastic energy have been taken into account. The equilibrium values of lattice strain and chemical potential have been calculated self-consistently for non-zero temperatures. Within the Green function approach, the energy spectrum has been calculated as function of model parameters, temperature and external pressure. Our results show that there exists a threshold value of the external pressure above which energy gap value decreases rapidly with temperature and system becomes a correlated metal.