Coordination-number defects and ring formulation of fullerenelike clusters produced by C-60-C-60 collision

Defect structures of fullerenes and fullerenelike clusters produced by two C-60 molecules colliding at differ ent impact parameters and different collision directions in the energy range 50-600 eV have been studied using a molecular-dynamics simulation method. The electronic structures around the defects are obtained using a self-consistent-field Hartree-Fock scheme. The results show that the numbers of coordination-number defects obey a magic rule, and the numbers of rings forming the closed cage structure of the fullerene or fullerenelike products can be well described by a modified formula deduced from Euler's theorem. The electronic structures around the defects are substantially changed in comparison with those of the carbon atoms on normal fullerene cages.