LATTICE DISTORTION AND ENERGY-LEVEL STRUCTURES IN DOPED C-70 BY THE EXTENDED SU-SCHRIEFFER-HEEGER MODEL

Lattice and electronic structures of undoped and doped C70 are investigated. The Su-Schrieffer-Heeger model is extended and solved numerically. For the undoped system, the results agree well with those of the local-density approximation by Saito and Oshiyama. When one or two electrons are added or removed, electronic structures show significant changes. It is predicted that the HOMO and LUMO of the undoped system intrude largely into the energy gap, just like a polaron in polyacetylene. The lattice pattern also deforms from that of the undoped system. Consequences for experimental studies are discussed.