 Crystal nucleation and growth of monodisperse hard spheres as a function of packing density is studied by collision-driven Molecular Dynamics simulations. We demonstrate, that short-range order in the form of sites with fivefold symmetry acts as an inhibitor to crystal growth. As a consequence, crystallization at high volume fractions is significantly delayed in random hardsphere packings where sites with fivefold symmetry are abundant. A cluster-based approach shows that configurations having initially a similar average fraction of fivefold sites can crystallize in completely different patterns both in terms of dynamics and morphology based on the half life of fivefold sites. The growth of a critical crystal nucleus is significantly affected by existing fivefold sites: it is observed that its shape and size evolves so as to avoid close proximity to regions rich in fivefolds. This trend could provide an explanation for the highly anisotropic shape of the critical nucleus observed in recent experiments and simulations and which is in contradiction with predictions of the classical nucleation theory. Eventually, once a given structure transits to the ordered phase, fivefold symmetry either diminishes or arranges in specific geometric patterns. Such defects are spatially strongly correlated with twinning planes at crystalline boundaries.
for LaTeX users @article{NCKarayiannis2012-8,
author = {N. C. Karayiannis and R. Malshe and M. Kr\"oger and J. J. de Pablo and M. Laso},
title = {Evolution of fivefold local symmetry during crystal nucleation and growth in dense hard-sphere packings},
journal = {Soft Matter},
volume = {8},
pages = {844-858},
year = {2012}
}
\bibitem{NCKarayiannis2012-8} N.C. Karayiannis, R. Malshe, M. Kr\"oger, J.J. de Pablo, M. Laso,
Evolution of fivefold local symmetry during crystal nucleation and growth in dense hard-sphere packings,
Soft Matter {\bf 8} (2012) 844-858.NCKarayiannis2012-8
N.C. Karayiannis, R. Malshe, M. Kr\"oger, J.J. de Pablo, M. Laso
Evolution of fivefold local symmetry during crystal nucleation and growth in dense hard-sphere packings
Soft Matter,8,2012,844-858 |
mk@mat.ethz.ch
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