Le Breton Guillaume, Joly Laurent
Département de Physique, École Normale Supérieure de Lyon, 46 Allée d'Italie, Lyon Cedex 07, France.
Univ. Lyon, Univ. Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France.
J Chem Phys. 2020 Jun 28;152(24):241102. doi: 10.1063/5.0011058.
Molecular dynamics simulations of aqueous electrolytes generally rely on empirical force fields, combining dispersion interactions-described by a truncated Lennard-Jones (LJ) potential-and electrostatic interactions-described by a Coulomb potential computed with a long-range solver. Recently, force fields using rescaled ionic charges [electronic continuum correction (ECC)], possibly complemented with rescaling of LJ parameters [ECC rescaled (ECCR)], have shown promising results in bulk, but their performance at interfaces has been less explored. Here, we started by exploring the impact of the LJ potential truncation on the surface tension of a sodium chloride aqueous solution. We show a discrepancy between the numerical predictions for truncated LJ interactions with a large cutoff and for untruncated LJ interactions computed with a long-range solver, which can bias comparison of force field predictions with experiments. Using a long-range solver for LJ interactions, we then show that an ionic charge rescaling factor chosen to correct long-range electrostatic interactions in bulk accurately describes image charge repulsion at the liquid-vapor interface, and the rescaling of LJ parameters in ECCR models-aimed at capturing local ion-ion and ion-water interactions in bulk- describes well the formation of an ionic double layer at the liquid-vapor interface. Overall, these results suggest that the molecular modeling of aqueous electrolytes at interfaces would benefit from using long-range solvers for dispersion forces and from using ECCR models, where the charge rescaling factor should be chosen to correct long-range electrostatic interactions.
水性电解质的分子动力学模拟通常依赖于经验力场，它结合了由截断的 Lennard-Jones（LJ）势描述的色散相互作用和由使用长程求解器计算的库仑势描述的静电相互作用。最近，使用重新缩放离子电荷的力场[电子连续介质校正（ECC）]，可能辅以 LJ 参数的重新缩放[ECC 重新缩放（ECCR）]，在本体研究中已显示出有前景的结果，但其在界面处的性能研究较少。在这里，我们首先探讨了 LJ 势截断对氯化钠水溶液表面张力的影响。我们展示了对于具有大截断的截断 LJ 相互作用的数值预测与使用长程求解器计算的未截断 LJ 相互作用的数值预测之间的差异，这可能会使力场预测与实验的比较产生偏差。然后，使用用于 LJ 相互作用的长程求解器，我们表明选择用于校正本体中长程静电相互作用的离子电荷重新缩放因子准确地描述了液 - 气界面处的镜像电荷排斥，并且 ECCR 模型中旨在捕获本体中局部离子 - 离子和离子 - 水相互作用的 LJ 参数重新缩放很好地描述了液 - 气界面处离子双层的形成。总体而言，这些结果表明，界面处水性电解质的分子建模将受益于使用长程求解器来处理色散力以及使用 ECCR 模型，其中应选择电荷重新缩放因子来校正长程静电相互作用。
