Fragmentation of C60, C70 by tight-binding molecular-dynamics approach

We have studied fragmentation of fullerenes using tight-binding molecular dynamics approach. The C60 and C70 molecules form floppy phase with fluctuations ± 0.4 إ at 3000 K but do not disintegrate. We observe that a window is opened at high temperature when a bond between pentagon and hexagon is broken, forming 9 membered rings, which may play an important role for the formation of endohedral fullerene compounds. Higher membered rings such as 13 and 16 membered rings are also found, forming larger windows. The C2, C4, and C5 are formed during the disintegration. Both form linked chains after complete disintegration at 5000 K. Possible explanation for the formation of fullerenes is given. We also find that the latent heat of C60 and C70 are 1.65 and 1.29 eV, respectively, larger than that of graphite (1.08 eV).