The molecular dynamics on the concentration fluctuations and the mutual diffusion coefficient in the supercritical solution

超临界溶液中浓度波动和相互扩散系数的分子动力学

• 批准号: 10640501
• 负责人: KATAOKA Yosuke
• 金额: $ 2.11万
• 依托单位: Hosei University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640501/
• 关键词: molecular dynamics; concentration fluctuation; Lennard-Jones mixture; mutual diffusion coefficient; supercritical solution; Kirkwood-Buff parameters; partial molar volume; correlation length; 超臨界溶液; レナード・ジョーンズ溶液; 動径分布関数

Molecular dynamics simulations on Lennard-Jones mixture in the supercritical region are performed. The first component is Ar and the other one is Kr. The simulations are done in the two cases. The first one is a 2-D system, where the cell length is longer for a given molecule number in the unit cell compared to that in the 3-D case. The other system is the 3-D one. In the later case, the number of the molecule in the unit cell is 23328 and the mole fraction is 0.5. The concentration fluctuations near the critical point are large compared to the ideal mixing in the both systems.The kinematic factor is obtained by the mean square displacement of the center of mass of the component 1. The thermodynamic factor is calculated by the radial distribution functions according to the Kirkwood-Buff theory. The mutual difusion coefficient is the product of the kinematic factor and thermodynamic one.The normalized mutual diffusion coefficient by the self-diffusion coefficient has small value near the critical density because of the large concentration fluctuation. The heat capacity, partial molar volume and correlation lengths of density and concentration in the supercritical region are compared with those at the normal density.

对Lennard-Jones混合物在超临界区进行了分子动力学模拟。第一种是Ar，另一种是Kr。在这两种情况下进行了模拟。第一种是2-D系统，与3-D情况相比，对于单位晶胞中给定的分子数，晶胞长度更长。另一个系统是3D系统。在后一种情况下，晶胞中的分子数为23328，摩尔分数为0.5。在两个体系中，临界点附近的浓度波动都比理想混合时大，运动学因子由组分1质心的均方位移求得。根据Kirkwood-Buff理论，用径向分布函数计算热力学因子。互扩散系数是运动学因子和热力学因子的乘积，由于浓度波动较大，由自扩散系数归一化的互扩散系数在临界密度附近较小。比较了超临界区和正常密度下的热容、偏摩尔体积、密度和浓度的关联长度。

项目成果

Ken-ichi Ago et al.: "Anomalous Behavior of Diffusion Coefficients near the Critical Point from Molecular Simulation"JCPE Journal. 11. 77-84 (1999)

Ken-ichi Ago 等人：“分子模拟临界点附近扩散系数的异常行为”JCPE 期刊。

山田祐理: "酢酸の二次元水素結合モデルのモンテカルロ法計算"法政大学計算科学研究センター研究報告. (印刷中). (2000)

Yuri Yamada：“乙酸二维氢键模型的蒙特卡罗计算”法政大学计算科学研究中心研究报告（2000 年出版）。

Yosuke Kataoka: "Anomalies in the concentration fluctuations and the mutual diffusion coefficient of 2-dimensional Lennard-Jones mixture in the supercritical region" Fluid Phase Equilibria. 144. 257-267 (1998)

Yosuke Kataoka：“超临界区二维 Lennard-Jones 混合物的浓度波动和相互扩散系数的异常”流体相平衡。

Yosuke Kataoka: "Anomalies in the concentration fluctuations and the mutual diffusion coefficient of 2-dimensional Lennard-Jones mixture in the supercritical region"Fluid Phase Equilibria. 144. 257-267 (1999)

Yosuke Kataoka：“超临界区二维Lennard-Jones混合物的浓度波动和相互扩散系数的异常”流体相平衡。

Yosuke Kataoka: "The concentration fluctuations and the mutual diffusion coefficient in the supercritical solution"J.Mol.Liquids. 印刷中. (2000)

Yosuke Kataoka：“超临界溶液中的浓度波动和相互扩散系数”J.Mol.Liquids 出版（2000）。