Bollinger Jonathan A, Jain Avni, Carmer James, Truskett Thomas M
McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
J Chem Phys. 2015 Apr 28;142(16):161102. doi: 10.1063/1.4919688.
We examine the structural and dynamic properties of confined binary hard-sphere mixtures designed to mimic realizable colloidal thin films. Using computer simulations, governed by either Newtonian or overdamped Langevin dynamics, together with other techniques including a Fokker-Planck equation-based method, we measure the position-dependent and average diffusivities of particles along structurally isotropic and inhomogeneous dimensions of the fluids. At moderate packing fractions, local single-particle diffusivities normal to the direction of confinement are higher in regions of high total packing fraction; however, these trends are reversed as the film is supercooled at denser average packings. Auxiliary short-time measurements of particle displacements mirror data obtained for experimental supercooled colloidal systems. We find that average dynamics can be approximately predicted based on the distribution of available space for particle insertion across orders of magnitude in diffusivity regardless of the governing microscopic dynamics.
我们研究了旨在模拟可实现的胶体薄膜的受限二元硬球混合物的结构和动力学性质。使用由牛顿动力学或过阻尼朗之万动力学控制的计算机模拟，以及包括基于福克 - 普朗克方程的方法在内的其他技术，我们测量了粒子沿流体结构各向同性和不均匀维度的位置相关扩散率和平均扩散率。在中等填充分数下，垂直于受限方向的局部单粒子扩散率在总填充分数高的区域更高；然而，当薄膜在更高平均密度下过冷时，这些趋势会反转。粒子位移的辅助短时间测量反映了实验过冷胶体系统获得的数据。我们发现，无论微观动力学如何，平均动力学都可以基于粒子插入可用空间的分布在扩散率的几个数量级上进行近似预测。
