Reasonable all-atom or united-atom biomolecular force fields have been developed to represent the properties of proteins and lipid membranes in molecular dynamics simulations. However, since they have not been parametrized for self-assembled monolayers (SAMs), their utility in simulating SAMs and protein–SAM systems has not been confirmed. Here, we compared six popular biomolecular force fields, Lipid14, GAFF, L-OPLS, CHARMM36, Slipids, and GROMOS54a7, to simulate alkanethiol SAMs of short to long chains (C10–C18). Our results show that none of these force fields reproduce the chain length dependence of the tilt angle, and twist angle. Although the droplet contact angles on SAMs are well represented by all force fields, only GAFF and Lipid14 yield phase transition temperatures that are reasonably close to the experimental values. Overall, our comprehensive comparison suggests that GAFF and Lipid14 are better choices for SAM simulations; further improvements in the force field parameters for SAMs are required. (152 words)

中文翻译：

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烷硫醇自组装单层模拟的生物分子力场的比较。

已经开发出合理的全原子或联合原子生物分子力场，以表示分子动力学模拟中蛋白质和脂质膜的特性。但是，由于尚未对自组装单分子膜（SAM）进行参数设置，因此尚未证实其在模拟SAM和蛋白质-SAM系统中的效用。在这里，我们比较了六个流行的生物分子力场，Lipid14，GAFF，L-OPLS，CHARMM36，Slipids和GROMOS54a7，以模拟短链至长链（C10–C18）的烷硫醇SAM。我们的结果表明，这些力场均不能再现倾斜角和扭曲角的链长依赖性。尽管所有力场都很好地表示了液滴在SAM上的接触角，但只有GAFF和Lipid14产生的相变温度相当接近实验值。全面的，我们的综合比较表明，GAFF和Lipid14是SAM模拟的更好选择。需要进一步改进SAM的力场参数。（152个字）