Abstract
A two-band hopping model is treated where one narrow band lies near the Fermi energy. As the size of an atomic orbit depends on the occupations of the atomic levels, an occupation-influenced hopping rate with a form factor is introduced. Correlations of a new type involving orbital and spin degrees of freedom build up. The possible phase transitions are studied by logarithmic approximation in one dimension. For particular range of the position of the Fermi energy, attractive interaction and supeconductivity are generated as a consequence of the form factor.