Computational studies of the growth mechanism of small fullerenes: A ring-stacking model

A ring-stacking model for the fullerene growth mechanism has been analyzed using the semiempirical AMI scheme. Following different routes, small fullerenes C₂₈ (T_d and D₂), C₂₆ (D _3h) and C₂₄ (D_6d) have been constructed from, monocyclic/polycyclic precursors and circumscribing them with appropriate carbon belts. The deformation, energies (DE) and the average bond lengths <R> of the precursors have been computed. The DE values suggest that there is a chance of bond cleavage of the polycyclic precursors as the growth process proceeds towards the cage formation. On the other hand, the monocyclic precursors are found to have significantly lower deformation energies than the polycyclic precursors. Further analyzing <R> values of the polycyclic and monocyclic cases at different stages, it is observed that the <R> values of the polycyclic cases decrease gradually, depicting a shrink in the precursors which may be detrimental to the growth process, whereas monocyclic precursors tend to swell, corroborating the tendency of the system to grow, which may be conducive for the growth process.