  Band structures of C60-polymers are studied changing conjugation conditions
and the electron number. We use a Su-Schrieffer-Heeger type semiempirical
model. In the neutral C60-polymer, electronic structures change among
direct-gap insulator and the metal, depending on the degree of conjugations.
The C60-polymer doped with one electron per one molecule is always a metal. The
energy difference between the highest-occupied state and the lowest-unoccupied
state of the neutral system becomes smaller upon doping owing to the polaron
effects. The C60-polymer doped with two electrons per one C60 changes from an
indirect-gap insulator to the direct-gap insulator, as the conjugations become
stronger.
