  Microscopic models of electronic subsystems with orbital degeneracy of energy
states and non-diagonal matrix elements of electron interactions (correlated
hopping) are considered within the configuration-operator approach. Equations
for arbitrary-temperature numerical calculation of the doublon concentration
for the integer band filling $n=1$ at different forms of the model density of
states are derived. The energy spectra obtained within the Green function
method are discussed with special emphasis on the role of correlated hopping in
transition from itinerant to localized behavior observed in vanadium Magneli
phases V$_n$O$_{2n-1}$, transition-metal dichalcogenides NiS$_{2-x}$Se$_x$,
fulleride A$_n$C$_{60}$ systems.
