We propose a unified approach to fit simultaneously a set of atomic partial charges and polarizabilities of the polarizable model against the ab initio electrostatic potential (ESP) and polarizability. The polarizable model is represented with interactive atomic dipoles with distance-dependent attenuation. For the polarizable model employed in this study, the internal electric field on the polarization sites is fully turned on, and thus allows self-induced dipoles, which persist even for an isolated molecule/ion. By such treatment, the contribution of ESP stems not only from the partial charges but also from the self-induced dipoles, and the atomic partial charges and polarizabilities can be fitted simultaneously against ESP in a unified manner. The fitting with 1-ethyl-3-methylimidazolium (EMIM⁺) and nitrate (NO₃^–), a prototypical organic cation and inorganic anion, respectively, that can form ionic liquid, demonstrates that allowance of the self-induced dipoles gives much better fitness. Moreover, test on the total dipole of an EMIM⁺/NO₃^– ion pair shows that the agreement with the ab initio dipole is also much improved for the polarizable model, which highlights the importance of the polarization effects of ionic liquids.

中文翻译：

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一种推导离子液体原子部分电荷和极化率的统一方法

我们提出了一种统一的方法来同时拟合可极化模型的一组原子部分电荷和极化率与从头算静电势 (ESP) 和极化率。可极化模型用具有距离相关衰减的交互式原子偶极子表示。对于本研究中使用的可极化模型，极化位点上的内部电场完全打开，因此允许自诱导偶极子，即使对于孤立的分子/离子也存在。通过这种处理，ESP的贡献不仅来自部分电荷，还来自自感偶极子，并且原子部分电荷和极化率可以以统一的方式同时与ESP拟合。1-乙基-3-甲基咪唑 (EMIM ⁺) 和硝酸盐 (NO ₃ ^– )，分别是典型的有机阳离子和无机阴离子，可以形成离子液体，这表明允许自诱导偶极子可以提供更好的适应度。^{此外，对EMIM +} /NO ₃ ^-离子对的总偶极子的测试表明，可极化模型与从头偶极子的一致性也得到了很大改善，这凸显了离子液体极化效应的重要性。