Electron Correlations in Narrow Energy Bands: Ground State Energy and Metal-Insulator Transition
arXiv:cond-mat/0005175
Abstract
The electron correlations in narrow energy bands are examined in framework of the Hubbard model. The single-particle Green function and energy spectrum are obtained in paramagnetic state at half-filling by means of new two-pole approximation. In the ground state analitical expressions for the energy gap, polar states concentration and energy of the system are found. Metal-insulator transitions in the model at change of bandwidth or temperature are investigated. The obtained results are used for interpretation of some experimental data in narrow-band materials.
12 pages, 11 eps figures, Latex 2.09