Multi-particle collision dynamics for a coarse-grained model of soft colloids
Multi-particle collision dynamics for a coarse-grained model of soft colloids
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DOI：
10.1063/1.5113588
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发表时间：
2019-08-21
影响因子：
4.4
通讯作者：
Zaccarelli, Emanuela
中科院分区：
文献类型：
--
作者：
Ruiz-Franco, Jose;Jaramillo-Cano, Diego;Zaccarelli, Emanuela
胶体悬浮液的动力学性质，无论是在平衡和外部驱动下，如剪切或压力流，需要准确的方法，正确地包括流体动力学效应，由于悬浮在溶剂中的发展日益增长的兴趣。在目前的工作中，我们推广的多粒子碰撞动力学（MPCD）能够处理软，聚合物胶体。我们的方法建立在知识的单体密度分布，可以从单体解析模拟没有流体力学或从理论上的论点。我们在此提出两种不同的方法。第一个简单地扩展了MPCD方法，包括在模拟中的有效单体具有给定的密度分布，从而忽略单体-单体相互作用。第二种认为大分子是一个单一的可渗透的软胶体（PSC），它是由一个不均匀分布的溶剂粒子渗透。通过定义一组适当的规则来控制溶剂和软胶体之间的碰撞事件，交换线动量和角动量。我们应用这些方法的情况下，线性链和星星聚合物为不同的单体长度和臂数，分别，并比较的结果与单体内得到的动力学性质解析模拟。我们发现，有效单体的方法工作良好的线性链，而PSC的方法提供了非常好的结果的明星。这些方法为将MPCD治疗扩展到复杂的大分子物体（如微凝胶或树枝状聚合物）以及在有限浓度下使用软胶体铺平了道路。
The growing interest in the dynamical properties of colloidal suspensions, both in equilibrium and under an external drive such as shear or pressure flow, requires the development of accurate methods to correctly include hydrodynamic effects due to the suspension in a solvent. In the present work, we generalize Multiparticle Collision Dynamics (MPCD) to be able to deal with soft, polymeric colloids. Our methods build on the knowledge of the monomer density profile that can be obtained from monomer-resolved simulations without hydrodynamics or from theoretical arguments. We hereby propose two different approaches. The first one simply extends the MPCD method by including in the simulations effective monomers with a given density profile, thus neglecting monomer-monomer interactions. The second one considers the macromolecule as a single penetrable soft colloid (PSC), which is permeated by an inhomogeneous distribution of solvent particles. By defining an appropriate set of rules to control the collision events between the solvent and the soft colloid, both linear and angular momenta are exchanged. We apply these methods to the case of linear chains and star polymers for varying monomer lengths and arm number, respectively, and compare the results for the dynamical properties with those obtained within monomer-resolved simulations. We find that the effective monomer method works well for linear chains, while the PSC method provides very good results for stars. These methods pave the way to extend MPCD treatments to complex macromolecular objects such as microgels or dendrimers and to work with soft colloids at finite concentrations.