ELECTRONIC-STRUCTURE OF THE SINGLY BONDED (C-60)(X) FULLERENE POLYMER

Electronic structure of the fullerene polymer consisting of singly bon ded units of fullerene molecules is a sensitive function of the charge state of the monomers. Assuming quasi-one-dimensionality of this pear l-necklace structure, we describe the electronic bands of this system with a simple quantum-mechanical method that was used previously to de scribe the ladder-type fullerene polymer of doubly bonded cages. We fi nd that the electronic structure of these two polymers is quite simila r, though in the ladder structure the cages bear one negative charge, while in the ''pearl-necklace'' polymer they are triply charged. Both systems exhibit a breakdown of translational periodicity via dimerizat ion, which is manifested in a charge- or spin-density wave and leads t o a band opening of 0.1 eV or less at the Fermi level. The calculation s confirm the existence of a prolongated covalent bond between the sin gly bonded polymeric units.