Title: ELECTRON CORRELATIONS IN NARROW ENERGY BANDS: GROUND STATE ENERGY AND METAL-INSULATOR TRANSITION
Author(s): L.Didukh, Yu.Skorenkyy (Ternopil State Technical University, Department of Physics, 56 Rus'ka Str., 46001 Ternopil, Ukraine; E-mail: didukh@tu.edu.te.ua, Tel.:+380352251946, Fax: +380352254983)

The electron correlations in narrow energy bands are examined within the framework of the Hubbard model. The single-particle Green function and energy spectrum are obtained in a paramagnetic state at half-filling by means of a new two-pole approximation. Analytical expressions for the energy gap, polar states concentration and energy of the system are found in the ground state. Metal-insulator transitions in the model at the change of bandwidth or temperature are investigated. The results obtained are used for interpretation of some experimental data in narrow-band materials.

Comments: Figs. 10, Refs. 27, Tabs. 0.