醇在水中的无限稀释扩散系数的分子动力学模拟

摘要

The infinite dilution diffusion coefficients (D12 )of some methanol,ethanol,and 1-propanol in water under the condition of 0.1 MPa and 298 ~318 K were simulated by molecular dynamics (MD) simulation.The microscopic structure and the intermolecular interaction was also analyzed by calculation of the radial distribution function,coordination number (CN)between the center mass of solute and sol-vent molecules,and the average number of hydrogen bond of this system.The simulated values are in ac-cordance with that of experiment.In addition,the peak height of radial distribution function,coordina-tion number,and average number of hydrogen bond all decrease with the increase of temperature,indica-ting that the accumulated water molecules around alkanol molecule decrease and the interaction between alkanol and water reduce.These factors jointly enhance diffusion coefficient.In general,this work pro-vides a reliable simulation method for transfer properties of solutes in water.At the same time,the results are helpful for one to deeper understand the relationship between microscopic structures of fluid and its transfer properties.%采用分子动力学（MD）模拟研究了0.1 MPa、298～318 K 条件下甲醇、乙醇、1－丙醇在水中的无限稀释扩散系数（D12），并通过径向分布函数、配位数、平均氢键数的计算，分析了二元流体的微观结构和分子间的相互作用。结果表明，模拟所得的无限稀释扩散系数与实验值符合。另外，随着温度升高，径向分布函数的峰高、醇分子与水分子之间的配位数以及醇－水的平均氢键数均减小，表明在较高温度下醇分子周围堆积的水分子数减少，醇分子和水分子之间的相互作用力降低，因而使扩散系数增大，这些结果从微观角度解释了扩散系数的变化规律。