Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany.
J Chem Phys. 2019 Feb 14;150(6):061102. doi: 10.1063/1.5082284.
Despite mounting evidence that the same gradients, which active colloids use for swimming, induce important cross-interactions (phoretic interactions), they are still ignored in most many-body descriptions, perhaps to avoid complexity and a zoo of unknown parameters. Here we derive a simple model, which reduces phoretic far-field interactions to a pair-interaction whose strength is mainly controlled by one genuine parameter (swimming speed). The model suggests that phoretic interactions are generically important for autophoretic colloids (unless effective screening of the phoretic fields is strong) and should dominate over hydrodynamic interactions for the typical case of half-coating and moderately nonuniform surface mobilities. Unlike standard minimal models, but in accordance with canonical experiments, our model generically predicts dynamic clustering in active colloids at a low density. This suggests that dynamic clustering can emerge from the interplay of screened phoretic attractions and active diffusion.
尽管越来越多的证据表明，主动胶体用于游动的相同梯度会引起重要的交叉相互作用（趋流相互作用），但在大多数多体描述中，它们仍然被忽略了，也许是为了避免复杂性和一堆未知参数。在这里，我们推导出一个简单的模型，将趋流远场相互作用简化为一种对相互作用，其强度主要由一个真正的参数（游动速度）控制。该模型表明，趋流相互作用对于自主胶体通常很重要（除非趋流场的有效屏蔽很强），并且对于半涂层和适度非均匀表面迁移率的典型情况，应该主导流体动力学相互作用。与标准最小模型不同，但与典型实验一致，我们的模型通常预测在低密度下活性胶体中的动态聚类。这表明动态聚类可以从屏蔽趋流吸引力和主动扩散的相互作用中产生。
