School of Chemistry and Chemical Engineering, Hainan Normal University, Haikou, 571158, People's Republic of China.
J Mol Model. 2013 Jan;19(1):73-82. doi: 10.1007/s00894-012-1514-0. Epub 2012 Jul 15.
Self-diffusion and structural properties of n-alkanes have been studied by molecular dynamics simulation in the temperature range between the melting pressure curve and 600 K at pressures up to 300 MPa. The simulated results of lower n-alkanes are in good agreement with the existing experimental data, and support the reliability of results of the simulations of self-diffusion coefficients obtained at the extreme conditions. We predict the self-diffusion coefficients for methane, ethane, propane and n-butane at the similar reduced temperatures and pressures to draw a comparison between them. Then the correlation between self-diffusion and structural properties are further investigated by calculating the coordination numbers. Moreover, we define four distances and their corresponding relative deviations to characterize the flexibility of long-chain n-alkanes. The simulated results show that the self-diffusion of n-alkane molecules is mainly affected by the close packing, and the flexibility has a strong impact on the self-diffusion of longer n-alkane molecules.
采用分子动力学模拟方法，在从熔融压力曲线到 600 K 的温度范围内、最高压力达 300 MPa 的条件下，研究了正构烷烃的自扩散和结构性质。较低正构烷烃的模拟结果与现有的实验数据吻合良好，支持在极端条件下获得的自扩散系数模拟结果的可靠性。我们预测了甲烷、乙烷、丙烷和正丁烷在类似的约化温度和压力下的自扩散系数，以便对它们进行比较。然后，通过计算配位数进一步研究了自扩散与结构性质之间的关系。此外，我们定义了四个距离及其相应的相对偏差，以表征长链正构烷烃的柔韧性。模拟结果表明，正构烷烃分子的自扩散主要受到紧密堆积的影响，而柔韧性对较长正构烷烃分子的自扩散有很强的影响。
