Characteristics of the LinC60 complexes for n=1-6 and 12: An ab initio study

Ab initio calculations have been performed for LinC60 where n = 1-6 and 12 using STO-3G and 6-31G basis sets. The distance between Li and the center of C-60 and geometrical parameters (bond lengths and bond angles) of C-60 have been fully optimized. Electronic structures and the HOMO-LUMO energy gap of the complexes have been analyzed. It was found that both basis sets yield results lying with the same trend. Compared to those in a free C-60 ligand, C-C and C=C bond lengths of C-60 in the LinC60 complexes change slightly for increasing n. The complexes with more Li also have an increased of Li-C-60 distance, except that for n = 12. In addition, the Li3C60 complex was found to exhibit the lowest energy gap among the investigated clusters. This is in good agreement with experimental observations for KnC60 and RbnC60 complexes and with the natural lattice structure of C-60, for which the unit cell contains two tetrahedral and one octahedral sites.