Algaba Jesús, Mendiboure Bruno, Gómez-Álvarez Paula, Blas Felipe J
Department of Chemical Engineering, Imperial College London South Kensington Campus London SW7 2AZ UK.
Laboratoire des Fluides Complexes et Leurs Reserviors, UMR5150, Université de Pau et des Pays de l'Adour B. P. 1155 Pau Cedex 64014 France.
RSC Adv. 2022 Jun 29;12(29):18821-18833. doi: 10.1039/d2ra02162e. eCollection 2022 Jun 22.
Recently, we have proposed the SAFT-VR Mie MF DFT approach [Algaba , , 2019, , 11937-11948] to investigate systems that exhibit fluid-fluid interfaces. This formalism is based on the combination of the Statistical Associating Fluid Theory for attractive potentials of variable range using Mie intermolecular potential (SAFT-VR Mie) and a Density Functional Theory (DFT) treatment of the free energy. A mean-field approach is used to evaluate the attractive term, neglecting the pair correlations associated to attractions. This theory has been combined with reported SAFT-γ Coarse-Grained (CG) Mie force fields to provide an excellent description of the vapor-liquid interface of carbon dioxide and water pure fluids. The present work is a natural and necessary extension of this previous study. We assess the adequacy of the proposed methodology for dealing with inhomogeneous fluid systems of large complex molecules, in particular carbon tetrafluoride and sulfur hexafluoride greenhouse gases, the refrigerant 2,3,3,3-tetrafluoro-1-propene, and the long-chain -decane and -eicosane hydrocarbons. The obvious diversity of these fluids, their chemical and industrial interest, and the fact of that SAFT-γ CG Mie force fields have been reported for them justify such choice. With the aim of testing the theory, we perform Molecular Dynamics simulations in the canonical ensemble using the direct coexistence technique for the same models. We focus both on bulk, such as coexistence diagrams and vapor pressure curves, as well as interfacial properties, including surface tension. The comparison of the theoretical predictions with the computational results as well as with experimental data taken from the literature demonstrates the reliability and generalization of this method for dealing simultaneously with vapor-liquid equilibrium and interfacial phenomena. Hence, it appears as a potential tool for the interface analysis, with the main advantage over molecular simulation of low computational cost, and solving the experimental difficulties in accurately measuring the surface tension of certain systems.
最近，我们提出了SAFT-VR Mie MF DFT方法[阿尔加巴，，2019，，11937 - 11948]来研究具有流体-流体界面的系统。这种形式体系基于使用米氏分子间势的可变范围吸引势的统计缔合流体理论（SAFT-VR Mie）与自由能的密度泛函理论（DFT）处理相结合。采用平均场方法来评估吸引项，忽略与吸引力相关的对关联。该理论已与已报道的SAFT-γ粗粒化（CG）米氏力场相结合，以出色地描述二氧化碳和水纯流体的气液界面。目前的工作是这项先前研究自然且必要的扩展。我们评估所提出的方法处理大型复杂分子非均匀流体系统的适用性，特别是四氟化碳和六氟化硫温室气体、制冷剂2,3,3,3 - 四氟 - 1 - 丙烯以及长链癸烷和二十烷烃。这些流体明显的多样性、它们在化学和工业方面的重要性，以及已报道了针对它们的SAFT-γ CG米氏力场这一事实证明了这种选择的合理性。为了检验该理论，我们使用直接共存技术在正则系综中对相同模型进行分子动力学模拟。我们既关注体相性质，如共存相图和蒸气压曲线，也关注界面性质，包括表面张力。将理论预测结果与计算结果以及从文献中获取的实验数据进行比较，证明了该方法在同时处理气液平衡和界面现象方面的可靠性和通用性。因此，它似乎是一种用于界面分析的潜在工具，相对于分子模拟的主要优势在于计算成本低，并且解决了准确测量某些系统表面张力的实验难题。
