Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.
Department of Applied Mathematics, University of California, Merced, California 95343, USA.
J Chem Phys. 2019 Sep 14;151(10):104101. doi: 10.1063/1.5113751.
We study the intrinsic nature of the finite system-size effect in estimating shear viscosity of dilute and dense fluids within the framework of the Green-Kubo approach. From extensive molecular dynamics simulations, we observe that the size effect on shear viscosity is characterized by an oscillatory behavior with respect to system size L at high density and by a scaling behavior with an L correction term at low density. Analysis of the potential contribution in the shear-stress autocorrelation function reveals that the former is configurational and is attributed to the inaccurate description of the long-range spatial correlations in finite systems. Observation of the long-time inverse-power decay in the kinetic contribution confirms its hydrodynamic nature. The L correction term of shear viscosity is explained by the sensitive change in the long-time tail obtained from a finite system.
我们在格林-库伯方法的框架内研究了有限系统尺寸效应对稀相和密相流体剪切黏度估计的内在性质。通过广泛的分子动力学模拟，我们观察到，在高密度下，剪切黏度的尺寸效应表现为与系统尺寸 L 的振荡行为，而在低密度下，则表现为具有 L 修正项的标度行为。对剪切应力自相关函数中势能贡献的分析表明，前者是构型的，归因于有限系统中长程空间相关性的不准确描述。对动力学贡献中长时间逆幂衰减的观测证实了其流体动力学性质。剪切黏度的 L 修正项可以通过从有限系统中获得的长时间尾部的敏感变化来解释。
