Journal Article Homogeneous SPC/E water nucleation in large molecular dynamics simulations

Angélil, Raymond  ,  Diemand, Jürg  ,  Tanaka, Kyoko K  ,  Tanaka, Hidekazu

143p.064507 , 2015-08-11 , American Institute of Physics (AIP)
We perform direct large molecular dynamics simulations of homogeneous SPC/E water nucleation, using up to ∼4 · 106 molecules. Our large system sizes allow us to measure extremely low and accurate nucleation rates, down to ∼1019 cm−3 s−1, helping close the gap between experimentally measured rates ∼1017 cm−3 s−1. We are also able to precisely measure size distributions, sticking efficiencies, cluster temperatures, and cluster internal densities.We introduce a new functional form to implement the Yasuoka-Matsumoto nucleation rate measurement technique (threshold method). Comparison to nucleation models shows that classical nucleation theory over-estimates nucleation rates by a few orders of magnitude. The semi-phenomenological nucleation model does better, under-predicting rates by at worst a factor of 24. Unlike what has been observed in Lennard-Jones simulations, post-critical clusters have temperatures consistent with the run average temperature. Also, we observe that post-critical clusters have densities very slightly higher, ∼5%, than bulk liquid. We re-calibrate a Hale-type J vs. S scaling relation using both experimental and simulation data, finding remarkable consistency in over 30 orders of magnitude in the nucleation rate range and 180 K in the temperature range.

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