Abstract
The 3465 classical isomers of C~64~ fullerene have been investigated by quantum chemical methods PM3, and the most stable isomers have been refined with HCTH/3‐21G//SVWN/STO‐3G, B3LYP/6‐31G(d)//HCTH/3‐21G, and B3LYP/6‐311G(d)//B3LYP/6‐31G(d) level. C~64~(D~2~:0003) with the lowest e~55~ (e~55~ = 2), the number of pentagon‐pentagon fusions, is predicted to be the most stable isomer and it is followed by the C~64~(C~s~:0077) and C~64~(C~2~:0103) isomers within relative energy of 20.0 kcal/mol. C~64~(D~2~:0003) prevails in a wide temperature range according to energy analysis with entropy contribution at B3LYP/6‐31G(d) level. The simulated IR spectra and electronic spectra help to identify different fullerene isomers. All the hexagons in the isomers with e~55~ = 2 display local aromaticity. The relative stabilities of C~64~ isomers change with charging in ionic states. Doping also affects the relative stabilities of fullerene isomers as demonstrated by Sc~2~@C~64~(D~2~:0003) and Sc~2~@C~64~(C~s~:0077). The bonding of Sc atoms with C~64~ elongates the CC bond of two adjacent pentagons and enhances the local aromaticity of the fullerene cages. Charging, doping, and derativization can be utilized to isolate C~64~ isomers through differentiating the electronic and steric effects. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008