Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan.
Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan.
J Chem Phys. 2014 Mar 21;140(11):114302. doi: 10.1063/1.4867909.
We performed molecular dynamics simulations of the nucleation of water vapor in order to test nucleation theories. Simulations were performed for a wide range of supersaturation ratios (S = 3-25) and water temperatures (T(w) = 300-390 K). We obtained the nucleation rates and the formation free energies of a subcritical cluster from the cluster size distribution. The classical nucleation theory and the modified classical nucleation theory (MCNT) overestimate the nucleation rates in all cases. The semi-phenomenological model, which corrects the MCNT prediction using the second virial coefficient of a vapor, reproduces the formation free energy of a cluster with the size ≲20 to within 10% and the nucleation rate and cluster size distributions to within one order of magnitude. The sticking probability of the vapor molecules to the clusters was also determined from the growth rates of the clusters. The sticking probability rapidly increases with the supersaturation ratio S, which is similar to the Lennard-Jones system.
我们进行了水蒸气成核的分子动力学模拟，以检验成核理论。模拟在很宽的过饱和度比（S=3-25）和水温（T（w）=300-390 K）范围内进行。我们从团簇尺寸分布中获得了亚临界团簇的成核速率和形成自由能。经典成核理论和修正的经典成核理论（MCNT）在所有情况下都高估了成核速率。半唯象模型使用蒸气的第二维里系数修正 MCNT 预测，将尺寸≲20 的团簇的形成自由能再现到 10%以内，将成核速率和团簇尺寸分布再现到一个数量级以内。从团簇的增长率也确定了蒸气分子对团簇的附着概率。附着概率随过饱和度比 S 的快速增加而增加，这与 Lennard-Jones 系统相似。
