Effect of bond length fluctuations on crystal nucleation of hard bead chains

Abstract

We study the effect of bond length fluctuations on the nucleation rate and crystal morphology of linear and cyclic chains of flexibly connected hard spheres using extensive molecular dynamics simulations. For bond length fluctuations as small as a tenth of the bead diameter, the relaxation and crystallization resemble those of disconnected spheres. For shorter bond lengths and chains with <10 beads the nucleation rates depend sensitively on the bond length, number of beads per chain, and chain topology, while for longer chains the nucleation rates are rather independent of chain length. Surprisingly, we find a nice data collapse of the nucleation rate as a function of the number of bonds per sphere in the system, independent of bead chain composition, chain length and topology. Hence, the crystal nucleation rate of bead chains can be enhanced by adding monomers to the system. We also find that the resulting crystal morphologies of bead chains with bond length fluctuations resemble closely those of hard spheres including structures with a five-fold symmetry.