Layer Structure of Doped C₆₀

It is found in this letter that the doped C₆₀ possesses layer-structure in both bond distortions and electronic states. There are eight layers of carbon atoms in the charged C₆₀, and its symmetry is reduced from I_h to D_5d. This layer-structure indicates that there exist four nonequivalent groups of carbon atoms in the doped C₆₀. It contrasts with the pristine C₆₀, in which all the sixty carbon atoms are equivalent. One observable consequence of such layer-structure is the split of its NMR spectrum with the ratio 1:1:2:2.