摘要
扩散系数在化工设计和研究中是不可缺少的传递特性。但其数据却相对缺乏,因此需要寻找一种方法来预测这个特性就显得十分重要。利用分子动力学方法模拟了简单流体的自扩散系数。模拟分别采用Green-Kubo法(VACF:velocity autocorrelation function)和Einstein法(MSD:mean square displacement)。模拟结果与实验数据吻合较好,误差在10%左右。两种方法的平均值与实验结果误差在7%左右。同时还模拟了流体自扩散系数随温度的变化关系。结果表明,自扩散系数与温度满足Arrenhius关系,数据相关性在0.99以上,计算得到的自扩散激活能分别为1 258 J/mol(VACF)、1 272 J/mol(MSD)和平均值1 265 J/mol。
Diffusion coefficient is indispensable to chemical engineering design and research. However, there is great lack of such data. By the means of molecular dynamics simulation, self-diffusion coefficient for simple fluid has been simulated using Green-Kubo relation （VACF： velocity autocorrelation function） and Einstein relation （MSD： mean square displacement）. The simulation results make good agreement with experimental findings except an error of about 10%. And, the average of simulation results of the two methods （average） reduces the error to 7%. The relation of diffusion coefficient with temperature has also been simulated. According to simulation results, whose correlation is all above 0. 99, diffusion coefficient agrees well with temperature following Arrenhius relation. Activation energy for self-diffusion has been calculated and the results are 1 258 J/mol （VACF）, 1 272 J/mol （MSD） and 1 265 J/mol （average） separately.
出处
《热科学与技术》
CAS
CSCD
2006年第2期101-105,共5页
Journal of Thermal Science and Technology
基金
国家自然科学基金委资助项目(50475100)
关键词
L-J流体
分子动力学
自扩散系数
数值模拟
激活能
Lennard-Jones fluid
molecular dynamics
self-diffusion coefficient
numerical simulation
activity energy
