Carrillo-Bohórquez Orlando, Kuroda Daniel G, Kumar Revati
Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, Louisiana 70803, USA.
J Chem Phys. 2024 Aug 7;161(5). doi: 10.1063/5.0214769.
A non-polarizable force field for lithium (Li+) and bis(trifluoromethanesulfonyl)imide (TFSI-) ions solvated in diglyme at around 0.2 mol fraction salt concentration was developed based on ab initio molecular dynamics (AIMD) simulations and a modified polymer consistent force field model. A force-torque matching based scheme, in conjunction with a genetic algorithm, was used to determine the Lennard-Jones (LJ) parameters of the ion-ion and ion-solvent interactions. This force field includes a partial charge scaling factor and a scaling factor for the 1-4 interactions. The resulting force field successfully reproduces the radial distribution function of the AIMD simulations and shows better agreement compared to the unmodified force field. The new force field was then used to simulate salt solutions with glymes of increasing chain lengths and different salt concentrations. The comparison of the MD simulations, using the new force field, with experimental data at different salt concentrations and AIMD simulations on equimolar concentrations of the triglyme system demonstrates the transferability of the force field parameters to longer glymes and higher salt concentrations. Furthermore, the force field appears to reproduce the features of the experimental x-ray structure factors, suggesting accuracy beyond the first solvation shell, for equimolar salt solutions using both triglyme and tetraglyme as the solvent. Overall, the new force field was found to accurately reproduce the molecular descriptions of LiTFSI-glyme systems not only at various salt concentrations but also with glymes of different chain lengths. Thus, the new force field provides a useful and accurate tool to perform in silico studies of this family of systems at the atomistic level.
基于从头算分子动力学（AIMD）模拟和改进的聚合物一致力场模型，开发了一种用于锂（Li +）和双（三氟甲磺酰）亚胺（TFSI -）离子在约0.2摩尔分数盐浓度下溶解于二甘醇二甲醚中的非极化力场。采用基于力 - 扭矩匹配的方案，并结合遗传算法，来确定离子 - 离子和离子 - 溶剂相互作用的 Lennard - Jones（LJ）参数。该力场包括部分电荷缩放因子和1 - 4相互作用的缩放因子。所得力场成功再现了AIMD模拟的径向分布函数，并且与未修改的力场相比显示出更好的一致性。然后使用新的力场来模拟链长增加且盐浓度不同的甘醇二甲醚盐溶液。使用新力场进行的分子动力学模拟与不同盐浓度下的实验数据以及三甘醇体系等摩尔浓度下的AIMD模拟的比较表明，力场参数可转移到更长链的甘醇二甲醚和更高盐浓度的体系。此外，对于使用三甘醇和四甘醇作为溶剂的等摩尔盐溶液，该力场似乎再现了实验X射线结构因子的特征，表明在第一溶剂化壳层之外也具有准确性。总体而言，发现新的力场不仅能在各种盐浓度下，而且能在不同链长的甘醇二甲醚体系中准确再现LiTFSI - 甘醇二甲醚体系的分子描述。因此，新的力场为在原子水平上对该类体系进行计算机模拟研究提供了一个有用且准确的工具。
