Robertson Bryan, Stark Holger, Kapral Raymond
Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
Chaos. 2018 Apr;28(4):045109. doi: 10.1063/1.5018297.
Collections of chemically propelled nanomotors free to move in solution can form dynamic clusters with diverse properties as a result of interactions through hydrodynamic flow and concentration fields, as well as direct intermolecular interactions between motors. Here, we study the collective rotational behavior of pinned sphere-dimer motors where direct motor-motor interactions play no role. Since the centers of mass of the motors are pinned, they cannot execute directed translational motion, but they can pump fluid and rotate; thus, the rotors remain coupled through hydrodynamic and chemical fields. Using a microscopic simulation method that accounts for coupling through both these fields, we show that different rotor configurations with a high degree of correlation exist and their forms depend on the nature of the fluid-rotor interactions. The correlations are greatly reduced or completely destroyed when the chemical interactions are removed, indicating that hydrodynamic coupling, while present, plays a lesser role in determining the collective rotor dynamics. These conclusions are supported by Langevin dynamics simulations that neglect hydrodynamics and include an approximate form of coupling through chemical fields.
化学驱动的纳米马达在溶液中自由移动的集合体，由于通过流体动力流和浓度场的相互作用以及马达之间的直接分子间相互作用，能够形成具有不同性质的动态簇。在此，我们研究固定的球形二聚体马达的集体旋转行为，其中马达之间的直接相互作用不起作用。由于马达的质心被固定，它们无法执行定向平移运动，但它们可以泵送流体并旋转；因此，转子通过流体动力和化学场保持耦合。使用一种考虑了通过这两个场进行耦合的微观模拟方法，我们表明存在具有高度相关性的不同转子构型，并且它们的形式取决于流体 - 转子相互作用的性质。当去除化学相互作用时，相关性会大大降低或完全破坏，这表明流体动力耦合虽然存在，但在确定集体转子动力学方面所起的作用较小。这些结论得到了朗之万动力学模拟的支持，该模拟忽略了流体动力学，并包括通过化学场的近似耦合形式。
