Title:A MODIFIED FORM OF THE POLAR MODEL OF CRYSTALS
Authors:L.Didukh (Ternopil State Technical University, Department of Physics, 56 Rus'ka St., UA-282001 Ternopil, Ukraine)

A model for the description of materials with narrow energy bands is proposed. It is shown that in narrow-band materials an electron-hole symmetry is absent in contrast to the Hubbard model. In this paper a metal-insulator transition is studied. The obtained results are compared with the experimental data for narrow-band materials. Some specific narrow-band effects are discussed.

Key words: narrow energy bands, model Hamiltonian, correlated hopping, electron-hole asymmetry
Comments: Figs. 1, Refs. 44, Tabs. 0.