Predicting Asphaltene Aggregate Structure from Molecular Dynamics Simulation: Comparison to Neutron Total Scattering Data
Predicting Asphaltene Aggregate Structure from Molecular Dynamics Simulation: Comparison to Neutron Total Scattering Data
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DOI：
10.1021/acs.energyfuels.8b03196
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发表时间：
2019-05-01
期刊：
影响因子：
5.3
通讯作者：
Hoepfner, Michael P.
中科院分区：
文献类型：
--
作者：
Headen, Thomas F.;Hoepfner, Michael P.
分子动力学（MD）模拟作为一种了解沥青质聚集体结构和动力学的技术正在迅速普及。然而，验证的模拟结果对实验数据，到目前为止，稀疏。在这里，我们提出了总散射数据阿萨巴斯卡沥青质，作为固体和分散在高浓度的氘代1-甲基萘。总散射的优点在于，可以根据问题系统中原子位置的知识来计算预期的散射，这意味着可以直接比较模拟和实验。我们发现，模型单分散系统的MD模拟再现散射曲线的一般形式，特别是分散沥青质的小角散射曲线的斜率和形状。然而，我们发现在文献中常用的MD技术的一些限制，特别是，形成的聚集体的大小是相当小的比从散射数据观察到的。我们确定这种差异的两个主要原因，即，有限的盒子大小，可以合理地模拟和缺乏分子的多分散性。
Molecular dynamics (MD) simulation is quickly growing in popularity as a technique for understanding asphaltene aggregate structure and dynamics. However, verification of the results of simulations against experimental data has, to date, been sparse. Here, we present total scattering data from Athabasca asphaltenes, as both a solid and dispersed at high concentrations in deuterated 1-methylnaphthalene. The advantage of total scattering is that the expected scattering can be calculated from knowledge of the atomic positions in the system of question, meaning that simulation and experiment can be directly compared. We find that the MD simulations for model monodisperse systems reproduce the general form of the scattering curves well, particularly for the slope and shape for the small-angle scattering curve of dispersed asphaltenes. However, we find a number of limitations in the MD techniques as commonly used in the literature; specifically, the size of the aggregates formed is considerably smaller than observed from the scattering data. We identify two main causes of this discrepancy, namely, the limited box size that can be reasonably simulated and the lack of molecular polydispersity.