Numerical Study of Growth and Relaxation of Small C-60 Nanoclusters

We investigate by means of kinetic Monte Carlo simulations the growth and thermal relaxation of small fullerene nanoclusters modelled by the Pacheco-Prates Ramalho pair potential. The activation barriers for diffusion processes are calculated on the fly by the dimer method. The elementary transitions which are likely to occur around room temperature are figured out. We study island growth on a perfect fullerene cluster and obtain a morphological transition of the island with increasing temperature. At T = 150 K, the islands are small and irregular. Around room temperature, elongated chain islands are obtained while at higher temperature, they are compact with an anti-Mackay stacking. These island morphologies have been shown to influence the character of the growth. Thus, growing fullerene clusters are disordered with rough surface below T = 300 K whereas at T = 450 K the growth occurs facet-by-facet within the growing shell.