QUANTUM-CHEMICAL STUDY OF C84 FULLERENE ISOMERS

Semiempirical and ab initio SCF calculations are reported for the C84 fullerenes with isolated pentagons. The optimized geometries and relative stabilities are discussed. All methods applied predict two nearly isoenergetic structures with D2 and D2d symmetry to be the most stable of the 24 isomers considered, which is consistent with the experimental observed C-13-NMR spectrum. Infrared spectra are predicted for these D2 and D2d isomers. The semiempirical results (MNDO, AM1, PM3) for the geometries and relative energies are in excellent agreement with the ab initio predictions at the split-valence SCF level.