Lennard-Jones 纯流体液汽界面的分子动力学模拟

Molecular dynamics simulation of theliquidvapor interface for pure LennardJones fluid

在表面张力长程校正公式的基础上，应用正则系综分子动力学模拟方法较为系统地对Ｌｅｎｎａｒｄ－Ｊｏｎｅｓ（ＬＪ）纯流体的液汽平衡及界面性质进行了模拟研究。在温度Ｔ＊＝ｋＢＴ／ε为０．７５～１．２０范围内，分别计算了７个温度条件下ＬＪ纯流体的汽液相共存平衡密度、密度分布、表面张力和界面厚度。研究结果表明：文中得到的ＬＪ纯流体汽液相平衡密度与采用Ｇｉｂｂｓ系综ＭｏｎｔｅＣａｒｌｏ模拟计算结果基本一致；表面张力的模拟计算值与实验数据符合较好；另外，随着温度的升高，流体的表面张力降低而界面厚度变大。

On the basis of longrange correction formula for surface tension, the liquidvapor equilibrium and interfacial properties of pure LennardJones (LJ) fluid have been studied systematically using molecular dynamics simulation method in the canonical ensemble. Seven runs were performed in the reduced temperature range from 0.75 to 1.20. The coexisting densities of equilibrium liquid and vapor phases, density profile, thickness of interface and surface tension for pure LJ fluid were obtained in each run. It has been found that the densities of liquid and vapor phases are in agreement with the results from the Gibbs ensemble Monte Carlo simulation. The values of surface tension from molecular dynamics simulation also match experimental data well. In addition, the thickness of liquidvapor interface increases as the temperature becomes higher, but the surface tension shows opposite tendency.