Heterogeneous crystallization on tiny clusters

The crystallization transition of an undercooled monodisperse Lennard-Jones fluid in the presence of small pre-structured seeds is studied with transition interface path sampling combined with molecular dynamics simulations. Compared to the homogeneous crystallization, clusters of 13 particles arranged into a face-centered cubic structure enhance the crystallization rate by one order of magnitude, while icosahedrally ordered seeds do not change the reaction rate at all. We identify two distinct nucleation regimes - close to the seed and in the bulk. Crystallites formed close to the seed attach to it, if it has face-centered cubic structure, and grow around the seed, if its structure is icosahedral. Copyright (C) EPLA, 2011