来自散射粒子动力学模拟的运输系数的格林-库博表达式被重新审视
D C Malaspina1, M Lísal2,3, J P Larentzos4
1Departament d'Enginyeria Química, ETSEQ, Universitat Rovira i Virgili, Tarragona 43007, Spain. josep.bonet@urv.cat.
Physical chemistry chemical physics : PCCP
|December 18, 2023
概括
格林-库博表达式适用于散射粒子动力学模拟,当物理性质保持不变,波动满足详细平衡时. 爱因斯坦-赫尔芬德关系为计算运输系数提供了一个更准确,更直接的方法.
科学领域:
- 计算物理 计算物理
- 软物质物理学 软物质物理学
- 化学工程是化学工程的重要组成部分.
背景情况:
- 在散射粒子动力学 (DPD) 模拟中应用格林-库博表达式来计算运输系数是有争议的.
- 分子动力学 (MD) 模拟传统上使用格林-库博表达式,但它们对DPD的直接应用需要仔细考虑特定条件.
研究的目的:
- 为了澄清DPD模拟中的Green-Kubo表达式的有效性和应用.
- 为了比较不同的运输系数计算方法,特别是切割粘度,在DPD.
- 为了确定DPD模拟的最准确和最有效的方法.
主要方法:
- 在维护物理性质和DPD中的详细平衡条件下,证明Green-Kubo表达式的有效性.
- 对剪切粘度计算的分析,将应力张量贡献分开,并处理依赖时间步骤 (δt) 的随机贡献.
- 推导的格林-库博表达式与恩斯特和布里托的公式进行比较,包括分析和数值验证.
主要成果:
- 如果动态模型保持所研究的物理性质,而波动满足详细平衡,那么Green-Kubo表达式将被验证为DPD.
- 随机贡献缩放为1/δt1/2可以使剪切粘度计算复杂化,如果应力张量未被分解.
- 衍生的格林-库博表达式在分析和数值上相当于恩斯特和布里托表达式,其差异归因于随机贡献的预平均值.
结论:
- 传统的Green-Kubo表达式在特定条件下适用于DPD模拟.
- 爱因斯坦-赫尔芬德关系为DPD中运输系数的计算提供了更强大,更准确的方法,避免了应力张量分解的需要.
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