de Miguel E, Almarza N G, Jackson G
Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain.
J Chem Phys. 2007 Jul 21;127(3):034707. doi: 10.1063/1.2751153.
We consider the computation of the surface tension of the fluid-fluid interface for the Widom-Rowlinson [J. Chem. Phys. 52, 1670 (1970)] binary mixture from direct simulation of the inhomogeneous system. We make use of the standard mechanical route, in which the surface tension follows from the computation of the normal and tangential components of the pressure tensor of the system. In addition to the usual approach, which involves simulations of the inhomogeneous system in the canonical ensemble, we also consider the computation of the surface tension in an ensemble where the pressure perpendicular (normal) to the planar interface is kept fixed. Both approaches are seen to provide consistent values of the interfacial tension. The issue of the system-size dependence of the surface tension is addressed. In addition, simulations of the fluid-fluid coexistence properties of the mixture are performed in the semigrand canonical ensemble. Our results are compared with existing data of the Widom-Rowlinson mixture and are also examined in the light of the vapor-liquid equilibrium of the thermodynamically equivalent one-component penetrable sphere model.
我们考虑通过对非均匀系统进行直接模拟来计算维道姆 - 罗林森二元混合物[《化学物理杂志》52, 1670 (1970)]的流体 - 流体界面的表面张力。我们采用标准的力学方法，其中表面张力可从系统压力张量的法向和切向分量的计算得出。除了涉及在正则系综中对非均匀系统进行模拟的常用方法外，我们还考虑在垂直于平面界面的压力保持固定的系综中计算表面张力。这两种方法都能给出一致的界面张力值。我们还探讨了表面张力对系统尺寸的依赖性问题。此外，在半巨正则系综中对该混合物的流体 - 流体共存性质进行了模拟。我们将结果与维道姆 - 罗林森混合物的现有数据进行了比较，并根据热力学等效的单组分可穿透球体模型的气 - 液平衡进行了检验。
