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Does Explicit Polarizability Improve Simulations of Phase Behavior of Ionic Liquids?
Journal of Chemical Theory and Computation ( IF 5.5 ) Pub Date : 2021-09-14 , DOI: 10.1021/acs.jctc.1c00518
Martin Klajmon 1 , Ctirad Červinka 1
Affiliation  

Molecular dynamics simulations are performed for a test set of 20 aprotic ionic liquids to investigate whether including an explicit polarizability model in the force field leads to higher accuracy and reliability of the calculated phase behavior properties, especially the enthalpy of fusion. A classical nonpolarizable all-atom optimized potentials for liquid simulations (OPLS) force-field model developed by Canongia Lopes and Pádua (CL&P) serves as a reference level of theory. Polarizability is included either in the form of Drude oscillators, resulting in the CL&P-D models, or in the framework of the atomic multipole optimized energetics for biomolecular application (AMOEBA) force field with polarizable atomic sites. Benchmarking of the calculated fusion enthalpy values against the experimental data reveals that overall the nonpolarizable CL&P model and polarizable CL&P-D models perform similarly with average deviations of about 30%. However, fusion enthalpies from the CL&P-D models exhibit a stronger correlation with their experimental counterparts. The least successful predictions are interestingly obtained from AMOEBA (deviation ca. 60%), which may indicate that a reparametrization of this force-field model is needed to achieve improved predictions of the fusion enthalpy. In general, all FF models tend to underestimate the fusion enthalpies. In addition, quantum chemical calculations are used to compute the electronic cohesive energies of the crystalline phases of the ionic liquids and of the interaction energies within the ion pair. Significant positive correlations are found between the fusion enthalpy and the cohesive energies. The character of the present anions predetermines the magnitude of individual mechanistic components of the interaction energy and related enthalpic and cohesive properties.

中文翻译:

显式极化率是否可以改善离子液体相行为的模拟?

对 20 种非质子离子液体的测试集进行了分子动力学模拟,以研究在力场中包含显式极化率模型是否会导致计算的相行为属性(尤其是聚变焓)的准确性和可靠性更高。由 Canongia Lopes 和 Pádua (CL&P) 开发的经典非极化全原子优化液体模拟势 (OPLS) 力场模型用作理论的参考水平。极化以 Drude 振荡器的形式包含在 CL&P-D 模型中,或者包含在具有可极化原子位点的用于生物分子应用的原子多极优化能量学 (AMOEBA) 力场的框架中。根据实验数据对计算的融合焓值进行基准测试表明,总体而言,不可极化 CL&P 模型和可极化 CL&P-D 模型的性能相似,平均偏差约为 30%。然而,来自 CL&P-D 模型的融合焓与其实验对应物表现出更强的相关性。有趣的是,最不成功的预测是从 AMOEBA 获得的(偏差约 60%),这可能表明需要对该力场模型进行重新参数化以实现对融合焓的改进预测。一般来说,所有 FF 模型都倾向于低估融合焓。此外,量子化学计算用于计算离子液体结晶相的电子内聚能和离子对内的相互作用能。在聚变焓和内聚能之间发现了显着的正相关。当前阴离子的特性预先决定了相互作用能和相关焓和内聚特性的各个机械分量的大小。
更新日期:2021-10-12
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