We perform molecular dynamics simulations to model density as a function of temperature for 74 alkanes with 5–10 carbon atoms and non-equilibrium molecular dynamics simulations in the NVT ensemble to model the kinematic viscosity of 10 linear alkanes as a function of molecular weight, pressure, and temperature. To model density, we perform simulations in the NPT ensemble before applying correction factors to exploit the systematic error in the SciPCFF force field and compare the results to experimental values, obtaining an average absolute deviation of 3.4 $\frac{\mathrm{g}}{\mathrm{l}}$ at 25 °C and of 7.2 $\frac{\mathrm{g}}{\mathrm{l}}$ at 100 °C. We develop a sampling algorithm that automatically selects good shear rates at which to perform viscosity simulations in the NVT ensemble and use the Carreau model with weighted least squares regression to extrapolate Newtonian viscosity. Viscosity simulations are performed at experimental densities and show an excellent agreement with experimental viscosities, with an average percent deviation of −1% and an average absolute percent deviation of 5%. Future plans to study and apply the sampling algorithm are outlined.

中文翻译：

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通过自动剪切速率采样来增强NEMD以对粘度进行建模以及对密度建模中的系统误差进行校正：应用于线性和轻度支链烷烃。

我们执行分子动力学模拟，以模拟74个具有5-10个碳原子的烷烃的密度随温度的变化，并在NVT集成中进行非平衡分子动力学模拟，以模拟10种线性烷烃的运动粘度随分子量，压力的变化和温度。为了对密度建模，我们在应用校正因子以利用SciPCFF力场中的系统误差并将结果与​​实验值进行比较之前，在NPT集合中执行模拟，从而获得平均绝对偏差为3.4$\frac{\mathrm{G}}{\mathrm{升}}$ 在25°C和7.2 $\frac{\mathrm{G}}{\mathrm{升}}$在100°C下。我们开发了一种采样算法，该算法可自动选择良好的剪切速率，以在NVT系综中执行粘度模拟，并使用具有加权最小二乘回归的Carreau模型外推牛顿粘度。粘度模拟是在实验密度下进行的，显示出与实验粘度的极佳一致性，平均偏差百分比为-1％，平均绝对偏差百分比为5％。概述了研究和应用采样算法的未来计划。