Ostadsharif Memar Zahra, Moosavi Majid
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.
Phys Chem Chem Phys. 2024 Oct 17;26(40):26109-26128. doi: 10.1039/d4cp03177f.
In this study, we investigated the effect of DFT density functionals and dispersion correction on an imidazolium-based dicationic ionic liquid (DIL) using molecular dynamics simulations. To achieve this purpose, the electronic structures, as well as the structural and dynamical properties of [C(mim)][NTF] DIL, were obtained using the BLYP and PBE functionals, both with and without D3-correction, and the results were compared with experimental values. Radial distribution functions and structure factors revealed that applying D3-correction increases the interaction between the anion and hydrogen atoms of the rings and side chains. The simulation of the studied DIL with the BLYP-D3 functional depicted lower structural heterogeneity compared to the other functionals. Analysis of Voronoi tessellation and linkage chain conformations showed a reduction in the aggregation of the linkage alkyl chains in the presence of D3-correction, which is more pronounced in the BLYP functional than in PBE. Additionally, it was observed that the probability of forming a hydrogen-bond network depends on both the type of used density functionals and applying dispersion correction. The results of dynamical properties, such as the self-diffusion coefficients, velocity autocorrelation function, and van Hove correlation function, as well as ion pair, ion cage, and hydrogen bond dynamics, indicated that applying D3-correction in both density functionals leads to an increase in the dynamics of the studied DIL. Additionally, the ratio of self-diffusion coefficients of the anion to the cation in the BLYP functional is closer to experimental values compared to the PBE functional. Furthermore, the electronic structure, including dipole moment distribution, and also infrared (IR) and power spectra were studied. Applying D3-correction and the type of density functionals have a significant effect on the dipole moment distribution of ions. Moreover, the results of IR and power spectra demonstrated that only in the BLYP functional, by applying D3-correction, the hydrogen bonding between the anion and the hydrogen atoms of the cation is strengthened at high wavenumbers. Thus, we conclude that applying D3 correction to both the BLYP and PBE density functionals improves the accuracy in describing the various properties of the studied system. Overall, the evaluation of different structural, dynamical, and vibrational properties of [C(mim)][NTF] DIL suggests that the BLYP-D3 density functional may be the best choice among the studied density functionals.
在本研究中，我们使用分子动力学模拟研究了密度泛函理论（DFT）密度泛函和色散校正对基于咪唑鎓的双阳离子离子液体（DIL）的影响。为实现这一目的，我们使用了带和不带D3校正的BLYP和PBE泛函来获得[C(mim)][NTF] DIL的电子结构以及结构和动力学性质，并将结果与实验值进行比较。径向分布函数和结构因子表明，应用D3校正会增加阴离子与环和侧链氢原子之间的相互作用。与其他泛函相比，用BLYP-D3泛函对所研究的DIL进行模拟显示出更低的结构异质性。对Voronoi镶嵌和连接链构象的分析表明，在存在D3校正的情况下，连接烷基链的聚集减少，这在BLYP泛函中比在PBE中更明显。此外，观察到形成氢键网络的概率既取决于所使用的密度泛函类型，也取决于应用色散校正。诸如自扩散系数、速度自相关函数和范霍夫相关函数等动力学性质的结果，以及离子对、离子笼和氢键动力学表明，在两种密度泛函中应用D3校正都会导致所研究DIL的动力学增加。此外，与PBE泛函相比，BLYP泛函中阴离子与阳离子的自扩散系数之比更接近实验值。此外，还研究了电子结构，包括偶极矩分布以及红外（IR）和功率谱。应用D3校正和密度泛函类型对离子的偶极矩分布有显著影响。此外，IR和功率谱的结果表明，仅在BLYP泛函中，通过应用D3校正，在高波数下阴离子与阳离子氢原子之间的氢键得到加强。因此，我们得出结论，对BLYP和PBE密度泛函都应用D3校正可提高描述所研究体系各种性质的准确性。总体而言，对[C(mim)][NTF] DIL的不同结构、动力学和振动性质的评估表明，BLYP-D3密度泛函可能是所研究密度泛函中的最佳选择。
