Structures of the Ca@C82 isomers: a theoretical prediction

Ab initio molecular orbital and nonlocal density functional calculations of Ca@C82 have been carried out to disclose in which cage isomers of C82 the Ca atom is encapsulated. Encapsulations inside the C2v, Cs, C2 and C3v cages are the most stable and close in energy. This agrees with the fact that four isomers have been isolated and purified for Ca@C82. It is suggested that the endohedral structures are determined during the annealing process.