Zheng Mei, Jaramillo-Botero Andres, Ju Xue-Hai, Goddard William A
Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, USA.
Phys Chem Chem Phys. 2021 May 14;23(18):10909-10918. doi: 10.1039/d0cp05767c. Epub 2021 Apr 28.
We developed a new coarse-grained (CG) molecular dynamics force field for polyacrylamide (PAM) polymer based on fitting to the quantum mechanics (QM) equation of state (EOS). In this method, all nonbond interactions between representative beads are parameterized using a series of QM-EOS, which significantly improves the accuracy in comparison to common CG methods derived from atomistic molecular dynamics. This CG force-field has both higher accuracy and improved computational efficiency with respect to the OPLS atomistic force field. The nonbond components of the EOS were obtained from cold-compression curves on PAM crystals with rigid chains, while the covalent terms that contribute to the EOS were obtained using relaxed chains. For describing PAM gels we developed water-PAM interaction parameters using the same method. We demonstrate that the new CG-PAM force field reproduces the EOS of PAM crystals, isolated PAM chains, and water-PAM systems, while successfully predicting such experimental quantities as density, specific heat capacity, thermal conductivity and melting point.
我们基于对量子力学（QM）状态方程（EOS）的拟合，开发了一种用于聚丙烯酰胺（PAM）聚合物的新型粗粒度（CG）分子动力学力场。在该方法中，使用一系列QM-EOS对代表性珠子之间的所有非键相互作用进行参数化，与源自原子分子动力学的常见CG方法相比，这显著提高了准确性。相对于OPLS原子力场，这种CG力场具有更高的准确性和更高的计算效率。EOS的非键成分是从具有刚性链的PAM晶体的冷压缩曲线获得的，而对EOS有贡献的共价项是使用松弛链获得的。为了描述PAM凝胶，我们使用相同的方法开发了水-PAM相互作用参数。我们证明，新的CG-PAM力场再现了PAM晶体、孤立的PAM链和水-PAM系统的EOS，同时成功预测了密度、比热容、热导率和熔点等实验量。
