Wróbel Piotr, Eilmes Andrzej
Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland.
Molecules. 2023 Sep 21;28(18):6736. doi: 10.3390/molecules28186736.
We investigated the performance of the computationally effective GFN2-xTB approach in molecular dynamics (MD) simulations of liquid electrolytes for lithium/sodium batteries. The studied systems were LiTFSI and NaTFSI solutions in ethylene carbonate or fluoroethylene carbonate and the neat solvents. We focused on the structure of the electrolytes and on the manifestations of ion-solvent interactions in the vibrational spectra. The IR spectra were calculated from MD trajectories as Fourier transforms of the dipole moment. The results were compared to the data obtained from ab initio MD. The spectral shifts of the carbonyl stretching mode calculated from the GFN2-xTB simulations were in satisfactory agreement with the ab initio MD data and the experimental results for similar systems. The performance in the region of molecular ring vibrations was significantly worse. We also found some differences in structural data, suggesting that the GFN2-xTB overestimates interactions of Me ions with TFSI anions and Na binding to solvent molecules. We conclude that the GFN2-xTB method is an alternative worth considering for MD simulations of liquids, but it requires testing of its applicability for new systems.
我们研究了计算效率高的GFN2-xTB方法在锂/钠电池液体电解质分子动力学（MD）模拟中的性能。所研究的体系是双（三氟甲基磺酰）亚胺锂（LiTFSI）和双（三氟甲基磺酰）亚胺钠（NaTFSI）在碳酸亚乙酯或氟代碳酸亚乙酯中的溶液以及纯溶剂。我们重点关注电解质的结构以及振动光谱中离子-溶剂相互作用的表现。红外光谱是根据MD轨迹通过偶极矩的傅里叶变换计算得出的。将结果与从头算MD得到的数据进行了比较。从GFN2-xTB模拟计算得到的羰基伸缩振动模式的光谱位移与从头算MD数据以及类似体系的实验结果吻合良好。在分子环振动区域的性能则明显较差。我们还发现了结构数据上的一些差异，这表明GFN2-xTB高估了甲基离子与双（三氟甲基磺酰）亚胺阴离子的相互作用以及钠与溶剂分子的结合。我们得出结论，GFN2-xTB方法是液体MD模拟中一个值得考虑的替代方法，但需要测试其对新体系的适用性。
