Temperature-dependent mechanisms of homogeneous crystal nucleation in quenched Lennard-Jones liquids: Molecular dynamics simulations

We have observed homogeneous crystal nucleation in Lennard-Jones liquid by molecular dynamics simulations. A clear nucleation time delay has been observed at T=0.677T_m and T=0.629T_m indicating the presence of a barrier, in contrast to recent reports [ Trudu et al. Phys. Rev. Lett. 97 105701 (2006)]. The structure of nuclei observed in the previous results and in the present work is evidence of transient-time dominated nucleation, not of a spinodal. Very rapid nucleation is observed at T=0.484T_m, indicating either a low (but finite) barrier or possibly a spinodal transformation. No spinodal effect has been observed in similar simulations of crystal nucleation in aluminum at any temperature [ Aga et al. Phys. Rev. Lett. 96 245701 (2006)], suggesting that different qualitative behaviors may be possible in what would seem to be similar potentials.