  Variations in the band structures of C60-polymers are studied, when
pi-conjugation conditions are changed. We look at band structures in order to
discuss a metal-insulator transition, using a semi-empirical model with the
Su-Schrieffer-Heeger type electron-phonon interactions. We find that electronic
structures change among direct-gap insulators and the metal, depending on the
degree of pi-conjugations. High pressure experiments could observe such
pressure-induced metal-insulator transitions.
