作为耗散粒子动力学的替代方法，Lowe-Andersen 恒温器可用于纠缠聚合物的介观模拟。

The Lowe-Andersen thermostat as an alternative to the dissipative particle dynamics in the mesoscopic simulation of entangled polymers.

机构信息

Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7202, USA.

出版信息

J Chem Phys. 2013 May 7;138(17):174903. doi: 10.1063/1.4802818.

Abstract

Dissipative Particle Dynamics (DPD) has shown a great potential in studying the dynamics and rheological properties of soft matter; however, it is associated with deficiencies in describing the characteristics of entangled polymer melts. DPD deficiencies are usually correlated to the time integrating method and the unphysical bond crossings due to utilization of soft potentials. One shortcoming of DPD thermostat is the inability to produce real values of Schmidt number for fluids. In order to overcome this, an alternative Lowe-Anderson (LA) method, which successfully stabilizes the temperature, is used in the present work. Additionally, a segmental repulsive potential was introduced to avoid unphysical bond crossings. The performance of the method in simulating polymer systems is discussed by monitoring the static and dynamic characteristics of polymer chains and the results from the LA method are compared to standard DPD simulations. The performance of the model is evaluated on capturing the main shear flow properties of entangled polymer systems. Finally the linear and nonlinear viscoelastic properties of such systems are discussed.

摘要

耗散粒子动力学（DPD）在研究软物质的动力学和流变性质方面显示出巨大的潜力；然而，它在描述缠结聚合物熔体的特性方面存在缺陷。DPD 的缺陷通常与时间积分方法和由于使用软势而导致的不物理键交叉有关。DPD 恒温器的一个缺点是无法为流体产生真实的施密特数值。为了克服这一点，本工作中使用了替代的 Lowe-Anderson (LA) 方法，该方法成功地稳定了温度。此外，引入了分段斥力势能以避免不物理键交叉。通过监测聚合物链的静态和动态特性来讨论该方法在模拟聚合物体系中的性能，并将 LA 方法的结果与标准 DPD 模拟进行比较。该模型的性能通过捕获缠结聚合物体系的主要剪切流动特性来评估。最后讨论了此类系统的线性和非线性粘弹性。