Duenas-Herrera Maria, Bonthuis Douwe Jan, Loche Philip, Netz Roland R, Scalfi Laura
Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
J Chem Phys. 2024 Aug 21;161(7). doi: 10.1063/5.0217998.
A classical non-polarizable force field for the common halide (F-, Cl-, Br-, and I-) and alkali (Li+, Na+, K+, and Cs+) ions in SPC/E water is presented. This is an extension of the force field developed by Loche et al. for Na+, K+, Cl-, and Br- (JPCB 125, 8581-8587, 2021): in the present work, we additionally optimize Lennard-Jones parameters for Li+, I-, Cs+, and F- ions. Li+ and F- are particularly challenging ions to model due to their small size. The force field is optimized with respect to experimental solvation free energies and activity coefficients, which are the necessary and sufficient quantities to accurately reproduce the electrolyte thermodynamics. Good agreement with experimental reference data is achieved for a wide range of concentrations (up to 4 mol/l). We find that standard Lorentz-Berthelot combination rules are sufficient for all ions except F-, for which modified combination rules are necessary. With the optimized parameters, we show that, although the force field is only optimized based on thermodynamic properties, structural properties are reproduced quantitatively, while ion diffusion coefficients are in qualitative agreement with experimental values.
本文提出了一种适用于SPC/E水中常见卤化物（F⁻、Cl⁻、Br⁻和I⁻）以及碱金属（Li⁺、Na⁺、K⁺和Cs⁺）离子的经典非极化力场。这是对Loche等人开发的适用于Na⁺、K⁺、Cl⁻和Br⁻的力场（《物理化学杂志B》125卷，8581 - 8587页，2021年）的扩展：在本工作中，我们额外优化了Li⁺、I⁻、Cs⁺和F⁻离子的 Lennard-Jones 参数。Li⁺和F⁻由于其尺寸小，是特别具有挑战性的离子，难以进行建模。该力场针对实验溶剂化自由能和活度系数进行了优化，这些是准确再现电解质热力学所需且充分的量。对于广泛的浓度范围（高达4 mol/l），与实验参考数据取得了良好的一致性。我们发现，标准的洛伦兹 - 贝塞洛特组合规则适用于除F⁻之外的所有离子，对于F⁻需要使用修正的组合规则。利用优化后的参数，我们表明，尽管该力场仅基于热力学性质进行了优化，但结构性质能够被定量再现，而离子扩散系数与实验值在定性上相符。
