ENERGETICS AND ISOMERIZATION PATHWAYS OF A LOWER FULLERENE - THE STONE-WALES MAP FOR C-40

Graph-theoretical and semi-empirical quantum-chemical results are combined to give a picture of the energetics and isomerisations of a typical lower fullerene, C-40. 38 of the 40 distinct fullerene isomers of C-40 are connected by Stone-Wales (pyracylene) transformations; the isomer of lowest total energy (as calculated by the QCFF/PI method) has the smallest number of fused pentagon pairs, and elimination of pentagon adjacencies by successive pyracylene rearrangements takes all other connected C-40 fullerenes downhill to the optimal isomer.