Classical molecular mechanics force fields typically model interatomic electrostatic interactions with point charges or multipole expansions, which can fail for atoms in close contact due to the lack of a description of penetration effects between their electron clouds. These short-range penetration effects can be significant and are essential for accurate modeling of intermolecular interactions. In this work we report parametrization of an empirical charge charge function previously reported (Piquemal, J.-P.; et al. J. Phys. Chem. A 2003, 107, 10353) to correct for the missing penetration term in standard molecular mechanics force fields. For this purpose, we have developed a database (S101X7) of 101 unique molecular dimers, each at 7 different intermolecular distances. Electrostatic, induction/polarization, repulsion, and dispersion energies, as well as the total interaction energy for each complex in the database are calculated using the SAPT2+ method (Parker, T. M.; et al. J. Chem. Phys. 2014, 140, 094106). This empirical penetration model significantly improves agreement between point multipole and quantum mechanical electrostatic energies across the set of dimers and distances, while using only a limited set of parameters for each chemical element. Given the simplicity and effectiveness of the model, we expect the electrostatic penetration correction will become a standard component of future molecular mechanics force fields.
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机译：经典的分子力学力场通常以点电荷或多极膨胀来模拟原子间静电相互作用，由于缺乏对电子云之间渗透作用的描述，原子紧密接触可能会失败。这些短程穿透效应可能很重要，并且对于分子间相互作用的精确建模至关重要。在这项工作中，我们报告了先前报道的经验电荷电荷函数的参数化（Piquemal，J.-P .;等人，J。Phys。Chem。A 2003，107，10353），以校正标准分子力学中缺失的渗透项力场。为此，我们开发了一个数据库（S101X7），该数据库包含101个独特的分子二聚体，每个分子间有7个不同的分子间距离。使用SAPT2 +方法（Parker，TM; et al.J.Chem.Phys.2014，140，094106）计算数据库中每个复合物的静电，感应/极化，排斥和分散能以及总相互作用能）。这种经验渗透模型可以极大地改善点二极和量子机械静电能在整个二聚体和距离范围内的一致性，而每个化学元素仅使用一组有限的参数。鉴于该模型的简单性和有效性，我们预计静电渗透校正将成为未来分子力学力场的标准组成部分。
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