DFT Study on the Interaction of the Smallest Fullerene C20 with Lithium Ions and Atoms

The smallest fullerene C20 with positive electron affinity is considered to be a new organic nano-electronic material. The binding structures and electronic states of lithium ions and atoms (Li+ and Li) trapped on the surface of C20 have been investigated by means of density functional theory (DFT) calculation to elucidate the nature of their interaction. It was found that a Li+ can bind to only one site of C20. This is, specifically, on top of the site where Li+ binds to the carbon atom of C20. On the other hand, in the case of a Li atom, two structures were obtained besides the on-top structure. One was pentagonal structure which included a Li atom on a five-membered ring of C20. The other was a triangular structure in which the Li atom bind to the the carbon–carbon bond of C20. Finally, the nature of the interactions between Li ions or atoms and the C20 cluster was discussed on the basis of theoretical results.