Impurity effects on nucleation of supercooled Lennard-Jones melt: A molecular dynamics study

We investigated the nucleation process of Lennard-Jones melts in the presence of various kinds of impurities by molecular dynamics simulations. Using a system that included a solvophobic impurity, which interacts weakly with solvent molecules, cluster formation barely occurred around the impurity. The induction time to reach critical cluster size increased with increasing solvophobic impurity size. In contrast, in a system including a solvophilic impurity, the cluster preferentially formed around the impurity irrespective of the impurity size. However, the induction time was significantly longer than the pure system when the impurity size was either two or four atoms. The results cannot be explained by a simple thermodynamic discussion of the effects of impurities and suggest that the kinetics of an impurity molecule could play an important role in the nucleation process.