Singh Sanjeet Kumar, Noroozi Ali, Soldera Armand
Department of Chemistry, Université de Sherbrooke, Sherbrooke, Quebec J1K2R1, Canada.
J Chem Phys. 2025 Apr 14;162(14). doi: 10.1063/5.0249333.
In spite of the tremendous increase in computational power over the last few decades, the problem of simulating atomistic systems containing large amounts of water molecules over longer lengths and time scales still remains. In this respect, the coarse-grained (CG) force field reduces the computational cost and, therefore, allows simulations of larger systems for longer times. However, the specific scope of the different CG water models is more limited compared to their atomistic counterparts. In this context, we conducted a comparative study on the molecular physical structure, thermodynamic, and dynamic properties of bulk water systems using six distinct CG water models and all-atom (AA) simulations. The six CG simulation procedures involved modeling with three variants of the water model coming from the MARTINI force field, one from the SPICA force field, and the two Iterative Boltzmann Inversion (IBI) derived potentials from the AA simulations. The AA simulations have been performed using the SPC/E and TIP4P force fields. The IBI models, namely SPC/E-IBI and TIP4P-IBI, depict the structural features in close agreement with the atomistic samples. The explicit number of water molecules in the first coordination shell for the three MARTINI models and the SPICA force field is in excellent agreement with the SPC/E and TIP4P values. The ensuing simulated densities for the various water models align significantly with the literature data, indicating the reliability of our approach. The SPC/E and SPICA models stand out in predicting the enthalpy of vaporization among the all-atom and CG force fields, respectively. The two all-atom models and their IBI equivalents are better at representing the isobaric specific heat capacity compared to the other models. The isothermal compressibility is reproduced comprehensively by the SPC/E force field followed by TIP4P, while SPICA is the better choice within the CG models. With respect to the dynamics of the system, the diffusion coefficient of the SPICA force field is in perfect agreement with the experimental data, even better than the atomistic samples. The overall scores of the different models, indicative of their relative performances compared to the other models, have also been computed.
尽管在过去几十年里计算能力有了巨大提升，但在更长的长度和时间尺度上模拟包含大量水分子的原子系统的问题仍然存在。在这方面，粗粒化（CG）力场降低了计算成本，因此能够对更大的系统进行更长时间的模拟。然而，与原子模型相比，不同的CG水模型的具体适用范围更为有限。在此背景下，我们使用六种不同的CG水模型和全原子（AA）模拟，对体相水系统的分子物理结构、热力学和动力学性质进行了比较研究。这六种CG模拟程序包括使用来自MARTINI力场的三种水模型变体、一种来自SPICA力场以及从AA模拟中导出的两种迭代玻尔兹曼反演（IBI）势进行建模。AA模拟使用了SPC/E和TIP4P力场。IBI模型，即SPC/E - IBI和TIP4P - IBI，所描绘的结构特征与原子样本非常吻合。三种MARTINI模型和SPICA力场在第一配位层中的水分子明确数量与SPC/E和TIP4P值高度一致。随后，各种水模型的模拟密度与文献数据显著吻合，表明我们方法的可靠性。在全原子和CG力场中，SPC/E和SPICA模型分别在预测汽化焓方面表现突出。与其他模型相比，这两种全原子模型及其IBI等效模型在表示等压比热容方面表现更好。SPC/E力场对等温压缩率的再现最为全面，其次是TIP4P，而在CG模型中SPICA是更好的选择。关于系统的动力学，SPICA力场的扩散系数与实验数据完全吻合，甚至比原子样本还要好。还计算了不同模型的总体得分，以表明它们与其他模型相比的相对性能。
