Molecular Modelling of Ionic Liquids: Situations When Charge Scaling Seems Insufficient

作者：Zhaoxi Sun, Lei Zheng, Zuo-Yuan Zhang, Yalong Cong, Mao Wang, Xiaohui Wang, Jingjing Yang, Zhirong Liu, Zhe Huai · 发表于：Molecules · 年份：2023 · DOI：10.3390/molecules28020800 · 被引用次数：15 · 研究领域：Ionic liquids properties and applications、Phase Equilibria and Thermodynamics、Electrochemical Analysis and Applications

Charge scaling as an effective solution to the experiment-computation disagreement in molecular modelling of ionic liquids (ILs) could bring the computational results close to the experimental reference for various thermodynamic properties. According to the large-scale benchmark calculations of mass density, solvation, and water-ILs transfer-free energies in our series of papers, the charge-scaling factor of 0.8 serves as a near-optimal option generally applicable to most ILs, although a system-dependent parameter adjustment could be attempted for further improved performance. However, there are situations in which such a charge-scaling treatment would fail. Namely, charge scaling cannot really affect the simulation outcome, or minimally perturbs the results that are still far from the experimental value. In such situations, the vdW radius as an additional adjustable parameter is commonly tuned to minimize the experiment-calculation deviation. In the current work, considering two ILs from the quinuclidinium family, we investigate the impacts of this vdW-scaling treatment on the mass density and the solvation/partition thermodynamics in a fashion similar to our previous charge-scaling works, i.e., scanning the vdW-scaling factor and computing physical properties under these parameter sets. It is observed that the mass density exhibits a linear response to the vdW-scaling factor with slopes close to -1.8 g/mL. By further investigating a set of physiochemically relevant temperat...