Zhang Li, Wang Qi, Liu Ying-Chun, Zhang Lian-Zhong
Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China.
J Chem Phys. 2006 Sep 14;125(10):104502. doi: 10.1063/1.2244547.
The structural organization, the number of hydrogen bonds (H bond), and the self- and mutual diffusion coefficients of ethanol-water mixtures were studied by molecular dynamics simulation. It was found that both the numbers of H bonds per water and per ethanol decrease as the mole fraction of ethanol increases. The composition dependences and the relationships between the self- and the mutual diffusion coefficients were further discussed. The self-diffusion coefficient of water has a large drop as the concentration of ethanol increases from 0 to 0.3 and then it nearly keeps constant, while that of ethanol has a minimum around ethanol mole fraction of 0.5. The mutual diffusion coefficient could be divided into two parts, the kinematic factor and the thermodynamic factor. Both the kinematic and thermodynamic factors for ethanol-water mixtures were calculated. It was found that the change trend of mutual diffusion coefficients with the composition is mainly dependent on the thermodynamic factors.
通过分子动力学模拟研究了乙醇 - 水混合物的结构组织、氢键数量以及自扩散系数和互扩散系数。研究发现，随着乙醇摩尔分数的增加，每个水分子和每个乙醇分子的氢键数量均减少。进一步讨论了自扩散系数和互扩散系数的组成依赖性及其相互关系。当乙醇浓度从0增加到0.3时，水的自扩散系数大幅下降，然后几乎保持恒定，而乙醇的自扩散系数在乙醇摩尔分数约为0.5时达到最小值。互扩散系数可分为两部分，即运动学因子和热力学因子。计算了乙醇 - 水混合物的运动学因子和热力学因子。结果发现，互扩散系数随组成的变化趋势主要取决于热力学因子。
