Cluster-model DFT simulations of the infrared spectra of triazine-based molecular crystals
Cluster-model DFT simulations of the infrared spectra of triazine-based molecular crystals
复制标题
三嗪基分子晶体红外光谱的簇模型 DFT 模拟
DOI：
10.1039/c8cp01550c
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发表时间：
2018
影响因子：
3.3
通讯作者：
Dongli Yu
中科院分区：
文献类型：
--
作者：
Xiaohong Yuan;Kun Luo;Nan Liu;Xueqiang Ji;Chao Liu;Julong He;Guangjun Tian;Yuanchun Zhao;Dongli Yu
从晶体堆积的角度理解分子间相互作用对分子材料科学具有重要意义。红外（IR）光谱可以提供互补的结构信息，然而，它仍然是一个巨大的挑战，以准确地预测分子的红外振动在结晶相。在这里，我们报告了一个集团模型的方法来模拟红外光谱的三嗪类分子晶体通过密度泛函理论（DFT）计算。在适当设计的簇模型中，分子IR振动由代表性单元表示，而最近邻分子被视为“冻结壳”来模拟周围的晶体学环境。通过考虑晶胞中的晶体学等效性，可以构建小得多的簇，这能够对更复杂的晶体结构进行DFT计算，并且具有可承受的计算成本。模拟的光谱显示出良好的一致性与实验的，特别是提供了一个深入的理解密切相关的氢键的振动模式。最重要的是，基于晶胞中晶体学独立分子的选择性构建的簇使我们能够进行特定的IR光谱模拟，通过这些模拟，首次清楚地揭示了它们独特的氢键环境。
Understanding the intermolecular interactions in the context of crystal packing is of fundamental significance in molecular materials science. Infrared (IR) spectroscopy can provide complementary structural information; however, it still remains a great challenge to accurately predict the molecular IR vibrations in the crystalline phase. Here we report a cluster-model approach to simulate the IR spectra of triazine-based molecular crystals via density functional theory (DFT) calculations. In the properly designed cluster models, the molecular IR vibrations are expressed by a representative unit, while the nearest-neighbouring molecules are treated as a “frozen shell” to mimic the surrounding crystallographic environments. Much smaller clusters can be built by considering the crystallographic equivalence in the unit cell, which are able to perform DFT calculations on more complicated crystal structures with endurable computational costs. The simulated spectra show excellent consistencies with the experimental ones, particularly providing an in-depth understanding of the vibrational modes closely related to hydrogen bonding. Most importantly, the selectively built clusters based on the crystallographically independent molecules in the unit cell allow us to perform specific IR-spectral simulations, by which their distinct hydrogen-bonding environments have been clearly revealed for the first time.