Simulated dynamics of Ne@C60 aggregates beyond dissociation

Abstract

Molecular dynamics (MD) computer simulations are utilized to better understand the dynamics of small (N = 5) endohedral Ne@C60 aggregates. Multiple runs at various temperatures are used to increase the reliability of our statistics. The aggregate holds together until somewhere between T = 1150 and 1200 K, where it dissociates, showing no intermediate sign of melting or fullerene disintegration. When the temperature is increased to around T = 4000 K, the encapsulated neon atoms begin to leave the aggregate, with the fullerene molecules still remaining intact. At temperatures near T = 4400 K, thermal disintegration of the fullerenes preempts the aggregate dissociation. Above this temperature neon atoms are more quickly released and the fullerenes form a larger connected structure, with bonding taking place in atom pairs from different original fullerene molecules. Escape constants and half lives are calculated for the temperature range 4000 K ≤ T ≤ 5000 K. The agreements and disagreements of results of this work with experiments suggest that classical MD simulations are useful in describing fullerene systems at low temperatures and near disintegration, but require development of new techniques before it is possible to accurately model windowing at temperatures below T = 3000 K.