论文标题
高度纠缠的各向同性模型聚合物熔体的多尺度平衡
Multiscale equilibration of highly entangled isotropic model polymer melts
论文作者
论文摘要
我们提出了一种计算高效的多尺度方法，用于制备平衡的各向同性长链模型聚合物熔体。作为一个应用程序，我们生成了$ 1000 $链条的Kremer-Grest融化，$ 200 $纠缠和$ 25000 $ - $ 2000 $的珠子每条链条，涵盖了与各向同性 - 纽扣过渡的限制的实验相关弯曲刚性。在第一步中，我们采用晶格模型的蒙特卡洛模拟来平衡试管尺度上方的大规模链结构，同时确保空间均匀的密度分布。然后，我们使用从约束模式管模型中使用理论见解来引入珠子自由度以及随机行走构象统计量一直到链条的库恩量表。接下来是一系列模拟序列，这些模拟具有仔细的参数化力限制的珠子弹簧模型，这些模型在各个级别的力限制下慢慢引入了局部珠子堆积，同时再现了目标kremer-grest系统的较大规模链统计。最后，我们可以切换到完整的kremer-grest模型而不会扰动结构。最终的链统计与在短链的蛮力模拟中访问的所有长度尺度上的文献结果非常吻合。
We present a computationally efficient multiscale method for preparing equilibrated, isotropic long chain model polymer melts. As an application we generate Kremer-Grest melts of $1000$ chains with $200$ entanglements and $25000$-$2000$ beads per chain, which cover the experimentally relevant bending rigidities up to and beyond the limit of the isotropic-nematic transition. In the first step, we employ Monte Carlo simulations of a lattice model to equilibrate the large-scale chain structure above the tube scale while ensuring a spatially homogeneous density distribution. We then use theoretical insight from a constrained mode tube model to introduce the bead degrees of freedom together with random walk conformational statistics all the way down to the Kuhn scale of the chains. This is followed by a sequence of simulations with carefully parameterized force-capped bead-spring models, which slowly introduce the local bead packing while reproducing the larger scale chain statistics of the target Kremer-Grest system at all levels of force-capping. Finally we can switch to the full Kremer-Grest model without perturbing the structure. The resulting chain statistics is in excellent agreement with literature results on all length scales accessible in brute-force simulations of shorter chains.
