Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, 19 Xin-Jie-Kou-Wai Street, Beijing 100875, China.
Phys Chem Chem Phys. 2021 Mar 21;23(11):6763-6774. doi: 10.1039/d1cp00032b. Epub 2021 Mar 15.
Coarse-grained (CG) molecular dynamics simulations are widely used to predict morphological structures and interpret mechanisms of mesoscopic behavior between the scope of traditional experiments and all-atom simulations. However, most current CG force fields (FFs) are not precise enough, especially for polar molecules or functional groups. A main obstacle in developing accurate CG FFs for polar molecules is the freezing problem met at room temperature. In this work, we introduce an indirect parametrization strategy for weakly polar groups by considering their short-chain homologs to avoid freezing. Here, a polar group containing three to four heavy atoms is mapped into one CG bead that is connected to one alkyl bead composed of three or four carbons. The CG beads interact via 4-parameter nonbonded Morse potentials and harmonic bonded potentials. An efficient meta-multilinear interpolation parameterization algorithm, as recently developed by us, is used to rigorously optimize the force parameters. Satisfactory accuracy is witnessed in terms of the density, heat of vaporization, surface tension, and solvation free energy of the homologs of twelve polar molecules, all deviating from the experiment by less than 5%. The transferability of the current FF is indicated by the predicted density, heat of vaporization, and end-to-end distance distributions of fatty acid methyl esters composed of multiple functional groups parameterized in this work.
粗粒化（CG）分子动力学模拟被广泛用于预测形态结构和解释介观行为机制，其范围在传统实验和全原子模拟之间。然而，目前大多数 CG 力场（FF）不够精确，特别是对于极性分子或官能团。开发用于极性分子的精确 CGFF 的主要障碍是在室温下遇到的冻结问题。在这项工作中，我们通过考虑它们的短链同系物来避免冻结，引入了一种用于弱极性基团的间接参数化策略。这里，含有三个到四个重原子的极性基团被映射到一个 CG 珠子上，该珠子与由三个或四个碳原子组成的一个烷基珠子相连。CG 珠子通过 4-参数非键 Morse 势和调和键势相互作用。最近由我们开发的高效元线性插值参数化算法用于严格优化力参数。对于十二个极性分子的同系物的密度、汽化热、表面张力和溶剂化自由能，都见证了令人满意的准确性，所有这些都比实验值偏差小于 5%。通过对本工作中参数化的多个官能团组成的脂肪酸甲酯的密度、汽化热和末端到末端距离分布的预测，表明了当前 FF 的可转移性。
