用改进的密度泛函理论预测三元硬球混合物的结构

Structures of Ternary Hard-Sphere Fluids Predicted by an Improved Density Functional Theory

在Ronsenfeld的权重函数的基础上,在计算流体自由能密度时利用硬球混合物流体的Boublik-Mansoori- Canahan-Starling-Leland状态方程来代替硬球的定标粒子理论,从而得到了改进的密度泛函理论。结合测试粒子法,对不同组成的三元硬球混合物流体的径向分布函数进行了计算;与分子模拟数据比较结果表明,使用合适的密度泛函理论,测试粒子法能够成功地计算多元硬球混合物流体的结构性质。 本研究为使用统计力学理论计算其它复杂流体的热力学性质提供了一种方法。

Based on the weight functions of Ronsenfeld, an improved density functional theory was obtained by using the excess Helmholtz energy density from the Boublik-Mansoori-Canahan-Starling-Leland equation of state instead of that from the scaled particle theory. The obtained density functional theory was used to predict the radial distribution functions through the test-particle method for ternary hard-sphere mixtures with different diameters at various compositions. The calculated radial distribution functions are in excellent agreement with the computer simulation data available. The calculated results show that the test-particle method can be successfully used to predict the structure properties when the accurate density functional theory is adopted. The present work provides a method for investigating structural and thermodynamic properties of complex fluids by using the statistical mechanic theories. As an example, the molar volumes for the ternary system Ar+N2+CH4 were predicted by the Barker-Henderson perturbation theory using the radial distribution functions for hard sphere mixtures. The results were compared with the experimental values and good agreement was achieved.