Yasuoka Kenji, Zeng X C
Department of Mechanical Engineering, Keio University, Yokohama 223-8522, Japan.
J Chem Phys. 2007 Mar 28;126(12):124320. doi: 10.1063/1.2712436.
A molecular dynamics simulation of vapor phase nucleation has been performed with 40,000 Lennard-Jones particles for the target gas and 0-160,000 particles for the carrier gas. Three carrier gas models are adopted, including a soft-core model, a Lennard-Jones model, and a modified Lennard-Jones model in which the attractive interaction can be adjusted. The effect of the carrier-gas pressure is assessed through computing and comparing the rate of nucleation and cluster size distribution. It is found that the effect of the carrier-gas pressure can be strongly dependent on the carrier-gas model. A positive effect (enhancement of the nucleation rate) is found with the soft-core potential model, whereas negligible effect is found with the Lennard-Jones potential model. For the modified Lennard-Jones potential with a weak attractive interaction, the carrier-gas effect is positive. However, the effect is negligible with a stronger attractive interaction between the target and carrier-gas particles. A reason for the negligible effect is that the carrier-gas particles are adsorbed on the cluster surface when the density of target and carrier-gas particles are comparable. When the density of carrier-gas particles are four times that of the target particles, the carrier-gas particles tend to mix with the target particles in the clusters.
利用40000个用于目标气体的Lennard-Jones粒子和0 - 160000个用于载气的粒子进行了汽相成核的分子动力学模拟。采用了三种载气模型，包括软核模型、Lennard-Jones模型以及一种可调节吸引相互作用的修正Lennard-Jones模型。通过计算和比较成核速率与团簇尺寸分布来评估载气压力的影响。发现载气压力的影响可能强烈依赖于载气模型。在软核势模型中发现了正向影响（成核速率增强），而在Lennard-Jones势模型中发现影响可忽略不计。对于具有弱吸引相互作用的修正Lennard-Jones势，载气效应是正向的。然而，当目标粒子与载气粒子之间的吸引相互作用较强时，该效应可忽略不计。效应可忽略不计的一个原因是，当目标粒子和载气粒子的密度相当时，载气粒子会吸附在团簇表面。当载气粒子的密度是目标粒子密度的四倍时，载气粒子倾向于与团簇中的目标粒子混合。
