Department of Chemical Engineering , Imperial College London, South Kensington Campus , London , SW7 2AZ , United Kingdom.
School of Chemical Engineering and Analytical Science , The University of Manchester , Oxford Road , Manchester , M13 9PL , United Kingdom.
J Phys Chem B. 2018 Oct 4;122(39):9161-9177. doi: 10.1021/acs.jpcb.8b04095. Epub 2018 Sep 24.
The SAFT-γ Mie group-contribution equation of state [ Papaioannou J. Chem. Phys. 2014 , 140 , 054107 ] is used to develop a transferable coarse-grained (CG) force-field suitable for the molecular simulation of linear alkanes. A heterogroup model is fashioned at the resolution of three carbon atoms per bead in which different Mie (generalized Lennard-Jones) interactions are used to characterize the terminal (CH-CH-CH-) and middle (-CH-CH-CH-) beads. The force field is developed by combining the SAFT-γ CG top-down approach [ Avendaño J. Phys. Chem. B 2011 , 115 , 11154 ], using experimental phase-equilibrium data for n-alkanes ranging from n-nonane to n-pentadecane to parametrize the intermolecular (nonbonded) bead-bead interactions, with a bottom-up approach relying on simulations based on the higher resolution TraPPE united-atom (UA) model [ Martin ; , Siepmann J. Phys. Chem. B 1998 , 102 , 2569 ] to establish the intramolecular (bonded) interactions. The transferability of the SAFT-γ CG model is assessed from a detailed examination of the properties of linear alkanes ranging from n-hexane ( n-CH) to n-octadecane ( n-CH), including an additional evaluation of the reliability of the description for longer chains such as n-hexacontane ( n-CH) and a prototypical linear polyethylene of moderate molecular weight ( n-CH). A variety of structural, thermodynamic, and transport properties are examined, including the pair distribution functions, vapor-liquid equilibria, interfacial tension, viscosity, and diffusivity. Particular focus is placed on the impact of incorporating intramolecular interactions on the accuracy, transferability, and representability of the CG model. The novel SAFT-γ CG force field is shown to provide a reliable description of the thermophysical properties of the n-alkanes, in most cases at a level comparable to the that obtained with higher resolution models.
SAFT-γ Mie 基团贡献状态方程 [ Papaioannou J. Chem. Phys. 2014, 140, 054107 ] 用于开发适用于线性烷烃分子模拟的可转移粗粒 (CG) 力场。采用三碳珠子分辨率的杂基团模型，其中使用不同的 Mie（广义 Lennard-Jones）相互作用来表征末端（CH-CH-CH-）和中间（-CH-CH-CH-）珠子。该力场是通过组合 SAFT-γ CG 自上而下方法 [ Avendaño J. Phys. Chem. B 2011, 115, 11154 ] 开发的，使用从正壬烷到正十五烷的 n-烷烃的实验相平衡数据来参数化分子间（非键合）珠子-珠子相互作用，同时依赖于基于更高分辨率 TraPPE 统一原子 (UA) 模型的模拟的自下而上方法 [ Martin ； ， Siepmann J. Phys. Chem. B 1998, 102, 2569 ] 来建立分子内（键合）相互作用。通过详细检查从正己烷（n-CH）到正十八烷（n-CH）的线性烷烃的性质，评估了 SAFT-γ CG 模型的可转移性，包括对更长链（如 n-二十六烷（n-CH）和中等分子量的典型线性聚乙烯（n-CH））的描述可靠性的额外评估。检查了各种结构、热力学和输运性质，包括配分函数、汽液平衡、界面张力、粘度和扩散系数。特别关注的是，将分子内相互作用纳入 CG 模型对其准确性、可转移性和代表性的影响。新型的 SAFT-γ CG 力场被证明能够可靠地描述 n-烷烃的热物理性质，在大多数情况下，其准确性与更高分辨率模型相当。
