纳米级液滴的结构和界面性质的评估通过机械，化学和统计力学的方法进行了详细讨论，包括原始的发展在宏观和微观水平的密度泛函理论（DFT）。我们强调，任何方法，如经典的成核理论，这是基于一个纯粹的宏观观点不会导致一个可靠的表示时，滴的半径变得微观。与宏观弹性理论的分子水平延伸相对应的所谓的力学途径，在分子动力学模拟中特别流行，由于微观压力张量的定义中固有的模糊性，也似乎是不可靠的，这是几十年来已知的但经常被忽视的观察结果。在这种情况下，我们提出了一个非局部平均场DFT的Lennard-Jones（LJ）流体检查不同大小的滴。将我们的DFT预测与最近基于二阶涨落分析的模拟数据进行了比较[J. G. Sampayo等人，JCP 132，141101（2010）]揭示了两种处理的一致性。这一观察结果指出了小液滴中涨落效应的重要性，这与人们在受机械平衡定律支配的平面界面的情况下所观察到的情况相反。预测了LJ流体的小负托尔曼长度和表面张力随液滴半径的非单调行为。最后，托尔曼方法的有效性的限制，分子间电位的范围的影响，和气泡的行为进行了简要的讨论。
英文摘要：
The structural and interfacial properties of a nanoscopic liquid drops are assessed by means of mechanical, thermodynamical, and statistical mechanical approaches that are discussed in detail, including original developments at both the macroscopic level and the microscopic level of density functional theory (DFT). We emphasize that any approach, such as classical nucleation theory, which is based on a purely macroscopic viewpoint does not lead to a reliable representation when the radius of the drop becomes microscopic. The so-called mechanical route which corresponds to a molecular-level extension of the macroscopic theory of elasticity, and is particularly popular in molecular dynamics simulation, also appears to be unreliable due to the inherent ambiguity in the definition of the microscopic pressure tensor, an observation which has been known for decades but is frequently ignored. In this vein, we propose a non-local mean-field DFT for Lennard-Jones (LJ) fluids to examine drops of varying size. A comparison of the predictions of our DFT with the recent simulation data based on a second-order fluctuation analysis [J. G. Sampayo et al., JCP 132, 141101 (2010)] reveals the consistency of the two treatments. This observation points out the significance of fluctuation effects in small drops, in contrast to what one observes in the case of planar interfaces which are governed by the laws of mechanical equilibrium. A small negative Tolman length and a non-monotonic behaviour of the surface tension with the drop radius are predicted for the LJ fluid. Finally, the limits of a validity of the Tolman approach, the effect of the range of the intermolecular potential, and the behaviour of bubbles are briefly discussed.
Ultra-low effective interfacial tension between miscible molecular fluids
本文利用在稠密背景流体中旋转的液滴的变形来研究可混溶分子流体之间的有效界面张力。我们发现，足够低的界面张力，旋转液滴开发哑铃形状，两个大的头部连接一个较薄的中心体。我们表明，这种形状不仅取决于密度和粘度之间的对比度的下降和背景流体，但也对流体的分子结构，因此在他们的界面上开发的应力，由于不同的分子相互作用。我们系统地研究了哑铃形的水-甘油混合物液滴在纯甘油容器中旋转的动力学。通过开发一个模型的变形的基础上的平衡的剪切应力反对的变形，施加的法向应力的下降和有效的界面张力，我们利用的时间演变的液滴形状来测量EIT。我们的研究结果表明，水-甘油系统中的EIT比以前的实验测量报告低几个数量级，并且与[Phys. Rev. X 6，041057，2016]中提出的相场模型计算的值非常一致。
Dynamic Permeability in Metastable Droplet Interfacial Bilayers
University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；The Molecular Foundry（分子发现所）；University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校）
Statistics and morphologies of stable droplets in scalar active fluids
Institute for Theoretical Physics IV, University of Stuttgart（斯图加特大学理论物理第四研究所）；STFC Hartree Centre（英国科学与技术设施委员会哈特里中心）；H. H. Wills Physics Laboratory, University of Bristol（布里斯托尔大学H.H.威尔斯物理实验室）
本研究针对标量活性流体中稳定液滴的特性，通过数值模拟Active Model B+模型，验证了噪声对相转变的偏移作用，发现单一参数可调控液滴的数量、密度与分形维数，还观测到液滴相深处的六方晶格转变，完善了活性流体相分离的理论认知。
