软胶体粒子形成束晶的动力学模拟

Simulation on the Dynamic Process of Formation of Particle Cluster by Generalized Exponential Model

利用广义指数模型描述软胶体粒子,结合分子动力学模拟研究软胶体粒子形成束晶的动力学过程.通过等温压缩和等密度降温2个不同的过程,研究了束晶形成过程中结构变化特征和动力学路径对结构的影响规律.研究发现,与蒙特卡洛模拟结果相比,分子动力学模拟得到的结构随着密度的变化有明显的迟滞现象,这是由于考虑了真实的动力学因素引起的差异.此外,在相同温度和压力下通过不同的动力学路径得到的相结构不完全相同,这是由于动力学形成过程会对相结构产生很大的影响.

The generalized exponential model was used to describe the interaction between soft colloidal particles. The dynamic process of structure formation and transformation was investigated by molecular dynamics simulations. The characteristics of the structural transformation and the influence of thermodynamicpath on the final formed structure of cluster crystal were studied for two thermodynamic paths,isothermal compression and equidensity cooling,respectively. Compared with Monte Carlo simulation results,the structure transitionin molecular dynamics simulation has obvious hysteresis on changing density,which is due to a high free energy barrier between fcc2 and fcc3 structures. In addition,the phase structure under the same temperature and pressure is not exactly same through different thermodynamic paths.It is concluded that the dynamic formation process has a great influence on phase structure.