氩蒸气在球形固体颗粒上异质核化的分子动力学模拟

异质核化在大气中广泛存在, 但是其微观核化机理鲜为人知, 本文应用分子动力学方法模拟过热氩蒸气在纳米球形固体颗粒物上异质核化的动态特性, 讨论不同的冷却率对核化过程中系综温度、团簇分布、团簇大小以及核化速率的影响. 结果显示, 系综内蒸气的核化温度随着冷却率的增加而降低, 预先存在的球形固体颗粒在团簇的形成阶段起着重要的作用, 而且存在一个临界冷却率1.80×10^-9J·s^-1. 在该冷却率下, 在异质核化系综内均质核化出现, 并与异质核化共存, 但是异质核化在整个核化过程中仍然占主导地位.

Molecular Dynamics Simulation of Heterogeneous Nucleation of Argon Vapor onto a Spherical Solid Particle

Heterogeneous nucleation often occurs in the atmosphere, but its microscopic mechanism is mostly unknown. In our work, molecular dynamics simulations were performed to explore the dynamic characteristics of the heterogeneous nucleation of supersaturated argon vapor onto a spherical solid nanoparticle. We discuss the effect of the cooling rate on the evolution of the system temperature, the cluster distribution, the cluster size, and the nucleation rate during the nucleation process. Our results show that the pre-existing nucleus plays an important role in the cluster formation stage. Furthermore, in the system with a pre-existing heterogeneous nucleus, a critical cooling rate (1.8×10^-9J·s^-1) exists at which homogeneous nucleation emerges and coexists with heterogeneous nucleation but heterogeneous nucleation still dominates the entire nucleation process.