Abstract
The fullerene road to C6o must proceed through isomers which do not obey the Isolated Pentagon Rule (IPR). Stone Wales (SW) transformations are required to redistribute the pentagons to obtain the almost exclusively observed IPR icosa-hedral C60. We find a very high barrier for these transformations (over 6 eV), which make their occurrence rare during the annealing phase of C60 formation. Earlier we reported that the presence of a loosely bound single carbon atom reduces this barrier to 3.9 eV, making frequent pentagon rearrangements possible.