Quantum chemical molecular dynamics study of ``Shrinking'' of Hot Giant fullerenes

Abstract

We present a detailed analysis of size-down trajectories of the ``Shrinking Hot Giant'' road of fullerene formation, revealed before by our quantum chemical molecular dynamics simulations. It is found that shrinkage of giant fullerenes occurs in two stages, fall-off and pop-out stage, respectively, and that it is an irreversible process occurring naturally at high temperatures. The driving force behind the energetically unfavorable C-2 evaporation is the increase in entropy and pi-conjugation stabilization of the increasingly more spherical fullerene cages. A comparison of the theoretical results with existing experimental data shows the importance of annealing for the synthesis of smaller (C-60, C-70) fullerenes.