Enhancement of the predictive power of molecular dynamics simulations for the determination of self-diffusion coefficient and viscosity demonstrated for propane
Enhancement of the predictive power of molecular dynamics simulations for the determination of self-diffusion coefficient and viscosity demonstrated for propane
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DOI：
10.1016/j.fluid.2019.05.019
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发表时间：
2019-09-15
影响因子：
2.6
通讯作者：
Froeba, Andreas P.
中科院分区：
文献类型：
--
作者：
Higgoda, Ubaya A.;Hellmann, Robert;Froeba, Andreas P.
对于分子动力学（MD）模拟中常用的经典有效力场（FF）的开发和优化，通常需要实验数据。另一种完全预测的方法是使用简化的特定于对的、基于从头算的FF（AI-FF），其来自于零密度极限中的量子计算。这种方法，这可以成功地采用在我们最近的甲烷（CH 4）和二氧化碳（CO 2）的工作，还没有研究相对较大的系统，包括丙烷（C3 H8）。在本研究中，选择C3 H8作为模型系统，以评估相对于确定的自扩散系数和粘度的MD模拟的预测能力。为此，我们的新的简化的全原子AI-FF的半刚性版本被应用在从过热蒸气到气体状态和超临界区域到压缩液体状态的宽密度范围内。为了阐明AI-FF对C3 H8的计算动力学性质的影响，还使用常用的、有效的文献FF以TrapPE和OPLS的形式进行了代表所研究的热力学状态的第一次调查的相应MD模拟。与压缩液体状态的例外，它被发现，我们的从头算为基础的方法提高了预测结果的自扩散系数和粘度在所研究的热力学状态对应的压力（0.1和5）MPa之间和温度（293.15和403.15）K相比，使用有效的FF。这可以通过与基于从头计算的零密度极限下的计算和稀少的实验数据的比较来证明。可以看出，在我们的从头算基础上的FFs C3 H8以及CH 4和CO2的全原子和刚性或半刚性表示的组合适合于在宽密度范围内的动力学性质的可靠模拟。(C)2019 Elsevier B. V.版权所有。
For the development and optimization of classical effective force fields (FFs) commonly used in molecular dynamics (MD) simulations, often experimental data are required. An alternative fully-predictive approach is the use of simplified pair-specific, ab initio-based FFs (AI-FFs) derived from quantum calculations in the limit of zero density. This approach, which could successfully be employed in our recent work for methane (CH4) and carbon dioxide (CO2), has not been investigated for relatively large systems including propane (C3H8). In the present study, C3H8 was selected as model system to evaluate the predictive power of MD simulations with respect to the determination of the self-diffusion coefficient and viscosity. For this aim, a semi-rigid version of our new simplified all-atom AI-FF was applied over a broad density range from the superheated vapor to the gas state and supercritical region up to the compressed liquid state. To elucidate the effects of the AI-FF on the calculated dynamical properties of C3H8, corresponding MD simulations representing the first investigations for the studied thermodynamic states were also performed using commonly employed, effective literature FFs in the form of TraPPE and OPLS. With the exception of the compressed liquid state, it was found that our ab initio-based approach improves the prediction results for the self-diffusion coefficient and viscosity at the studied thermodynamic states corresponding to pressures between (0.1 and 5) MPa and temperatures between (293.15 and 403.15) K compared to the use of effective FFs. This could be demonstrated by comparison with the ab initio-based calculations at the limit of zero density and the scarce experimental data. It could be figured out that the combination of an all-atom and a rigid or semi-rigid representation in our ab initio-based FFs for C3H8 as well as CH4 and CO2 suits well for a reliable simulation of dynamical properties over a broad density range. (C) 2019 Elsevier B.V. All rights reserved.