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首页> 外文期刊>RSC Advances >Thermodynamic, structural and dynamic properties of ionic liquids [C4mim][CF3COO], [C4mim][Br] in the condensed phase, using molecular simulations
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Thermodynamic, structural and dynamic properties of ionic liquids [C4mim][CF3COO], [C4mim][Br] in the condensed phase, using molecular simulations

机译：离子液体[C4mim] [CF3COO]，[C4mim] [Br]在冷凝相中的热力学，结构和动力学性质，使用分子模拟

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In this work a series of thermodynamic, structural, and dynamical properties for the 1-butyl-3-methylimidazolium trifluoroacetate ([C _(4) mim][CF _(3) COO]) and 1-butyl-3-methylimidazolium bromide, ([C _(4) mim][Br]) ionic liquids (ILs) were calculated using Non-polarizable Force Fields (FF), parameterized using a methodology developed previously within the research group, for condensed phase applications. Properties such as the Vapor-Liquid Equilibrium (VLE) curve, critical points ( ρ _(c) , T _(c) ), Radial, Spatial and Combined Distribution Functions and self-diffusion coefficients were calculated using Equilibrium Molecular Dynamics simulations (EMD); other properties such as shear viscosities and thermal conductivities were calculated using Non-Equilibrium Molecular Dynamics simulations (NEMD). The results obtained in this work indicated that the calculated critical points are comparable with those available in the literature. The calculated structural information for these two ILs indicated that the anions interact mainly with hydrogen atoms from both the imidazolium ring and the methyl chain; the bromide anion displays twice the hydrogen coordination number than the oxygen atoms from the trifluoroacetate anion. Furthermore, Non-Covalent interactions (NCI index), determined by DFT calculations, revealed that some hydrogen bonds in the [C _(4) mim][Br] IL displayed similar strength to those in the [C _(4) mim][CF _(3) COO] IL, in spite of the shorter O ~(?) –H distances found in the latter IL. The majority of the calculated transport properties presented reasonable agreement with the experimental available data. Nonetheless, the self-diffusion coefficients determined in this work are under-estimated with respect to experimental values; however, by escalating the electrostatic atomic charges for the anion and cation to ±0.8 e , only for this property, a remarkable improvement was obtained. Experimental evidence was recovered for most of the calculated properties and to the best of our knowledge, some new predictions were done mainly in thermodynamic states where data are not available. To validate the FF, developed previously within the research group, dynamic properties were also evaluated for a series of ILs such as [C _(4) mim][PF _(6) ], [C _(4) mim][BF _(4) ], [C _(4) mim][OMs], and [C _(4) mim][NTf _(2) ] ILs.
机译：在这项工作中，三氟乙酸1-丁基-3-甲基咪唑鎓盐（[C _（4）mim] [CF _（3）COO]）和1-丁基-3-甲基咪唑鎓溴化物的一系列热力学，结构和动力学性质，（[C _（4）mim] [Br]）离子液体（ILs）使用非极化力场（FF）计算，并使用先前在研究组内开发的方法进行参数化，用于浓缩相应用。使用平衡分子动力学模拟（EMD）计算诸如汽液平衡（VLE）曲线，临界点（ρ_（c），T _（c）），径向，空间和组合分布函数以及自扩散系数等属性）;使用非平衡分子动力学模拟（NEMD）计算其他特性，例如剪切粘度和热导率。这项工作获得的结果表明，计算出的临界点与文献中的临界点相当。计算出的这两个离子分子的结构信息表明，阴离子主要与咪唑鎓环和甲基链上的氢原子相互作用。溴化物阴离子的氢配位数是三氟乙酸根阴离子的氧原子的两倍。此外，通过DFT计算确定的非共价相互作用（NCI指数）显示，[C _（4）mim] [Br] IL中的某些氢键显示出与[C _（4）mim]相似的强度。 [CF _（3）COO] IL尽管在后者的IL中具有较短的O〜（？）–H距离。计算出的大多数运输性质与实验可用数据显示出合理的一致性。然而，相对于实验值，这项工作中确定的自扩散系数被低估了。但是，通过将阴离子和阳离子的静电原子电荷提升至±0.8 e，仅出于此特性，获得了显着的改进。就大多数计算出的性质而言，实验证据已经恢复，据我们所知，一些新的预测主要是在没有数据的热力学状态下进行的。为了验证先前在研究组内开发的FF，还对一系列IL（例如[C _（4）mim] [PF _（6）]，[C _（4）mim] [BF]的动态特性进行了评估。 _（4）]，[C _（4）mim] [OMs]和[C _（4）mim] [NTf _（2）] IL。

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