Molecular dynamics simulation of coalescence behavior of carbon nanoparticle

Molecular dynamics simulations were conducted to investigate the coalescence mechanism of carbon nanoparticles. The analytical objects were two clusters composed of benzene, anthracene, phenanthrene or coronene molecules, and those clusters were placed next to each other. These numerical analyses used isoPAHAP potential to describe the intermolecular interaction and OPLS-AA potential to account for intramolecular interaction. Since the behavior below and above the melting point is entirely different, the melting point of the cluster was first determined. The coalescence behavior was investigated at temperatures 30 K below the melting point, 5 K below the melting point, and 50 K above the melting point. The coalescence of benzene clusters progressed through three stages: fast shrinking at 0-0.4 ns; gradual and constant shrinking at 0.4-4 ns; and little shrinking after 4 ns. This indicates that the coalescence of benzene clusters is analogous to that of inorganic nanoparticles. However, the number of coalescence stages of coronene clusters was more than four. The coronene cluster looked composed of 4-6 molecules of crystallites. Due to the strong interaction among molecules within crystallites, the diffusion of molecules in crystallites would hardly occur. Thus, the coalescence of coronene clusters would proceed with the breaking of crystallites.