Institut de Physique de Rennes, UMR CNRS 6251, Université Rennes 1, 263 avenue du Général Leclerc, 35042 Rennes, France.
J Chem Phys. 2012 Jan 14;136(2):024104. doi: 10.1063/1.3676056.
Surface tension is probably the most important interfacial property and a large number of techniques have been devoted to its calculation. Usually, this calculation is carried out using mechanical or thermodynamic definitions. The mechanical route uses an arbitrary choice to affect the contribution of the pairwise force. To overcome this arbitrariness, a thermodynamic route based on the area perturbation (test-area (TA) method) has been developed for the calculation of surface tension. The volume perturbation (VP) method provides an original route to compute the components of the pressure tensor. These two routes are developed from the perturbation theory leading to working expressions using exponential averages of energy. The use of exponential averages makes the calculation strongly dependent on the occurrence of low values of ΔU. Additionally, the decomposition of the energy to obtain local surface tension is nontrivial. From the explicit derivation of the partition function the exponential average is avoided providing an interesting alternative to TA, VP, and mechanical methods. To make a consistent comparison, we study the profiles of the surface tension along the direction normal to the surface for the different definitions and techniques in the cases of liquid-vapor interfaces of acids gases, binary, and apolar systems.
表面张力可能是最重要的界面性质，已经有大量的技术致力于其计算。通常，这种计算是使用机械或热力学定义进行的。机械途径使用任意选择来影响成对力的贡献。为了克服这种任意性，已经开发出了一种基于面积扰动的热力学途径（测试面积（TA）方法）来计算表面张力。体积扰动（VP）方法提供了一种计算压力张量分量的原始途径。这两种途径都是从扰动理论发展而来的，使用能量的指数平均值得到工作表达式。使用指数平均值使计算强烈依赖于ΔU 值的出现。此外，获得局部表面张力的能量分解并不简单。从分区函数的显式推导中避免了指数平均值，为 TA、VP 和机械方法提供了一个有趣的替代方案。为了进行一致的比较，我们研究了不同定义和技术在酸气体、二元和非极性系统的液-气界面情况下沿垂直于表面的方向上表面张力的分布。
