Electronic Structure of C78and C78-Graphite Cointercalation Compound

Abstract

We study the electronic structure of C 78 and that of C 78 -graphite cointercalation compound. First we show the electronic structure of five isomers of C 78 . Their geometric structures have been optimized by an empirical model potential and their electronic structure has been calculated using the tight-binding model. The C 2 v -symmetry C 78 , a major isomer experimentally extracted, is found to have a considerably deep lowest unoccupied state. Using this C 2 v C 78 , we design a stage-1 C 78 -graphite cointercalation compound. Its electronic structure calculated with the tight-binding model shows that the deep lowest unoccupied state of the C 2 v C 78 causes charge transfer from a graphite sheet to C 78 . Although the material is formed with only carbon atoms, C 78 -graphite cointercalation compound is the hole doped graphite intercalation compound.