Physics Department, Erciyes University 38039 Kayseri, Turkey.
J Chem Phys. 2012 Feb 14;136(6):064106. doi: 10.1063/1.3683443.
We combine the modified Tompa model with the van der Waals equation to study critical lines for an unequal size of molecules in a binary gas-liquid mixture around the van Laar point. The van Laar point is coined by Meijer and it is the only point at which the mathematical double point curve is stable. It is the intersection of the tricritical point and the double critical end point. We calculate the critical lines as a function of χ(1) and χ(2), the density of type I molecules and the density of type II molecules for various values of the system parameters; hence the global phase diagrams are presented and discussed in the density-density plane. We also investigate the connectivity of critical lines at the van Laar point and its vicinity and discuss these connections according to the Scott and van Konynenburg classifications. It is also found that the critical lines and phase behavior are extremely sensitive to small modifications in the system parameters.
我们将改进的 Tompa 模型与范德华方程相结合，研究范拉儿点附近二元气液混合物中分子大小不等时的临界线。范拉儿点是由 Meijer 创造的，它是唯一数学双重点曲线稳定的点。它是三重临界点和双临界端点的交点。我们计算了临界线作为 χ(1)和 χ(2)的函数，χ(1)和 χ(2)分别是 I 型分子和 II 型分子的密度，对于不同的系统参数值；因此，在密度-密度平面上呈现和讨论了全局相图。我们还研究了范拉儿点及其附近临界线的连通性，并根据 Scott 和 van Konynenburg 分类讨论了这些连接。还发现，临界线和相行为对系统参数的微小变化非常敏感。
