We study the response of single nanosized spherical colloids in electrolyte solution to an alternating electric field (AC field) by computer simulations. We use a coarse-grained mesoscopic simulation approach that accounts in full for hydrodynamic and electrostatic interactions as well as for thermal fluctuations. The solvent is modeled as a fluid of single Dissipative Particle Dynamics (DPD) beads, and the colloidal particle is modeled as a rigid body made of DPD beads. We compute the mobility and the polarizability of a single colloid and investigate systematically the effect of amplitude and frequency of the AC-fields. Even though the thickness of the Debye layer is not "thin" compared to the radius of the colloid, and the thermal fluctuations are significant, the results are in good agreement with the theoretical prediction of the Maxwell-Wagner-O'Konski theory, especially for uncharged colloids.
Characterizing emergent multiscale dynamics in colloidal nanoparticle gels
University of Michigan（密歇根大学）；University of Texas at Austin（德克萨斯大学奥斯汀分校）；University of Washington（华盛顿大学）；Deutsches Elektronen-Synchrotron DESY（德国电子同步辐射中心）
Electric double layer of colloidal particles in salt-free concentrated suspensions including non-uniform size effects and orientational ordering of water dipoles
Frequency-dependent magnetic susceptibility of magnetic nanoparticles in a polymer solution: a simulation study
磁性复合材料，即弹性体、聚合物凝胶或具有嵌入的磁性纳米颗粒的聚合物溶液，可用于许多技术和生物医学应用。然而，颗粒的磁性和（粘）弹聚合物基质的机械性能之间的耦合机制的微观细节仍然没有得到解决。在这里，我们研究了一个单域球形磁性纳米粒子，悬浮在聚合物溶液中的响应，以交变磁场。作为相互作用，我们只考虑排除体积与聚合物的相互作用和通过溶剂介导的流体动力学相互作用。采用线性响应Green-Kubo方法计算了交流极化率谱，研究了聚合物浓度和聚合物长度对极化率谱的影响。我们的数据与最近测量的典型磁性复合系统的交流磁化率进行了比较[Roeben等人，Colloid and Polymer Science，2014，2013- 2023]，并证明了流体动力学耦合在此类系统中的重要性。
