Lyra Emerson P, Franco Luís F M
School of Chemical Engineering, University of Campinas, 13083-852 Campinas, São Paulo, Brazil.
J Chem Phys. 2022 Sep 21;157(11):114107. doi: 10.1063/5.0109350.
Using theoretical and computational tools for predicting thermophysical properties of fluid systems and the soft matter has always been of interest to the physical, chemical, and engineering sciences. Certainly, the ultimate goal is to be able to compute these macroscopic properties from first-principles calculations beginning with the very atomic constitution of matter. In this work, Mie potential parameters were obtained through dimer interaction energy curves derived from ab initio calculations to represent methane and substituted-methane molecules in a spherical one-site coarse-grained model. Bottom-up-based Mie potential parameters of this work were compared with top-down-based ones from the statistical associating fluid theory (SAFT) models for the calculation of thermodynamic properties and critical point by molecular dynamics simulations and SAFT-VR Mie equation of state. Results demonstrated that bottom-up-based Mie potential parameters when averaging the Mie potential parameters of a representative population of conformers provide values close to the top-down-based ones from SAFT models and predict well properties of tetrahedral molecules. This shows the level of consistency embedded in the SAFT-VR Mie family of models and confers the status of a purely predictive equation of state for SAFT-VR Mie when a reasonable model is considered to represent a molecule of interest.
使用理论和计算工具来预测流体系统和软物质的热物理性质，一直是物理、化学和工程科学领域所关注的。当然，最终目标是能够从物质的原子构成出发，通过第一性原理计算来计算这些宏观性质。在这项工作中，通过从头算计算得出的二聚体相互作用能曲线获得了米氏势参数，以在球形单位点粗粒化模型中表示甲烷和取代甲烷分子。通过分子动力学模拟和SAFT-VR米氏状态方程，将这项工作中基于自底向上的米氏势参数与统计缔合流体理论（SAFT）模型中基于自顶向下的参数进行了比较，以计算热力学性质和临界点。结果表明，当对具有代表性的构象群体的米氏势参数进行平均时，基于自底向上的米氏势参数提供的值接近SAFT模型中基于自顶向下的参数，并能很好地预测四面体分子的性质。这显示了SAFT-VR米氏模型家族中所蕴含的一致性水平，并赋予了SAFT-VR米氏状态方程在考虑合理模型来表示感兴趣分子时作为纯预测性状态方程的地位。
