Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland.
Saint Petersburg Institute for Machine Sciences, the Russian Academy of Sciences, Saint Petersburg 199178, Russia.
Phys Rev E. 2017 Jan;95(1-1):012704. doi: 10.1103/PhysRevE.95.012704. Epub 2017 Jan 20.
Calculations of translational self-diffusion coefficient in free-standing smectic films during a series of layer-thinning transitions as the temperature is raised above the bulk smectic-A-isotropic transition have been carried out. A molecular model based upon the random walk theory is applied for calculating the translational diffusion coefficient (TDC) D_{∥} across the smectic film both in the bulk of the film, as well as in the vicinity of the bounding surfaces. Calculations of D_{∥} require the set of the orientational and translational order parameters (OPs) which have been obtained by using the extended McMillan approach with anisotropic forces. The effect of E on the orientational and translational OPs, as well as on the TDC of smectic films has been investigated. A reasonable agreement between the theoretically predicted and the experimentally obtained data on the TDC in the bulk of the partially fluorinated H10F5MOPP film has been obtained. We also found, in agreement with the experimentally observed behavior of D_{∥}(N)(N=25,13,11,10), that the translational diffusion coefficient in the bulk of the film gradually increases as the film thickness N is decreased.
已对在高于体相各向同性转变温度的情况下，一系列层减薄转变过程中自由支撑的近晶相膜中的平移自扩散系数的计算进行了研究。应用基于随机游动理论的分子模型来计算在膜体相中和边界附近的近晶膜中平移扩散系数（TDC）D_{∥}。计算 D_{∥}需要一组取向和平移序参数（OPs），这些参数是通过使用具有各向异性力的扩展 McMillan 方法获得的。研究了 E 对近晶膜的取向和平移 OPs 以及 TDC 的影响。在部分氟化 H10F5MOPP 膜体相中，理论预测和实验获得的 TDC 数据之间存在合理的一致性。我们还发现，与 D_{∥}(N)(N=25,13,11,10)的实验观察行为一致，随着膜厚度 N 的减小，膜体相中平移扩散系数逐渐增加。
