Department of Creative Engineering, Tsuruoka College, National Institute of Technology, 104 Sawada, Inooka, Tsuruoka, Yamagata 997-8511, Japan.
Department of Applied Physics, National Defense Academy, 1-10-20, Hashirimizu, Yokosuka 239-8686, Japan.
J Chem Phys. 2018 Sep 21;149(11):114901. doi: 10.1063/1.5046755.
A model is developed for simulating entangled polymers by dissipative particle dynamics (DPD) using the segmental repulsive potential (SRP). In contrast to previous SRP models that define a single-point interaction on each bond, the proposed SRP model applies a dynamically adjustable multipoint on the bond. Previous SRP models could not reproduce the equilibrium properties of Groot and Warren's original DPD model [R. D. Groot and P. B. Warren, J. Chem. Phys. , 4423 (1997)] because the introduction of a single SRP induces a large excluded volume, whereas, the proposed multipoint SRP (MP-SRP) introduces a cylindrical effective excluded bond volume. We demonstrate that our MP-SRP model exhibits equilibrium properties similar to those of the original DPD polymers. The MP-SRP model parameters are determined by monitoring the number of topology violations, thermodynamic properties, and the polymer internal structure. We examine two typical DPD polymers with different bond-length distributions; one of them was used in the modified SRP model by Sirk [J. Chem. Phys. , 134903 (2012)], whereas the other was used in the original DPD model. We demonstrate that for both polymers, the proposed MP-SRP model captures the entangled behaviors of a polymer melt naturally, by calculating the slowest relaxation time of a chain in the melt and the shear relaxation modulus. The results indicate that the proposed MP-SRP model can be applied to a variety of DPD polymers.
提出了一种用耗散粒子动力学（DPD）通过分段排斥势（SRP）模拟缠结聚合物的模型。与以前在每个键上定义单点相互作用的 SRP 模型不同，所提出的 SRP 模型在键上应用动态可调多点。以前的 SRP 模型无法再现 Groot 和 Warren 原始 DPD 模型的平衡性质[R.D.Groot 和 P.B.Warren，J.Chem.Phys.，4423（1997）]，因为引入单点 SRP 会导致较大的排斥体积，而所提出的多点 SRP（MP-SRP）则会引入圆柱形有效排斥键体积。我们证明，我们的 MP-SRP 模型表现出与原始 DPD 聚合物相似的平衡性质。MP-SRP 模型参数通过监测拓扑违规次数、热力学性质和聚合物内部结构来确定。我们检查了两种具有不同键长分布的典型 DPD 聚合物；其中一个被 Sirk 用于修改后的 SRP 模型[J.Chem.Phys.，134903（2012）]，而另一个则用于原始 DPD 模型。我们证明，对于这两种聚合物，所提出的 MP-SRP 模型通过计算熔体中链的最慢松弛时间和剪切松弛模量，自然地捕获了聚合物熔体的缠结行为。结果表明，所提出的 MP-SRP 模型可应用于各种 DPD 聚合物。
