Wang Shaoqing
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
Sci Rep. 2020 Oct 21;10(1):17875. doi: 10.1038/s41598-020-74872-6.
Vibrational assignment, which establishes the correspondence between vibrational modes and spectral frequencies, is a key step in any spectroscopic study. Due to the lack of experimental technique to directly observe the thermal vibration of atoms, the assignment is usually done by empirical trial-and-error method with considerable uncertainty. Here we demonstrate a successful study of intrinsic molecular vibration property based on first-principles molecular dynamics trajectory. A unified approach for calculating and assigning vibrational frequencies is developed and applied to solve some historical issues of benzene vibration. As a major achievement, the experimental frequencies of benzene a and b vibrations are reassigned, which breaks a deadlock in contemporary spectroscopic science and removes a cloud over the application of density-functional theory in organic chemistry. This work paves the way for the comprehensive realization of the first-principles spectroscopic research, and provides crucial clues to solve the century-old problems of Kekule resonance, π-deformation, and aromaticity.
振动归属，即确定振动模式与光谱频率之间的对应关系，是任何光谱研究中的关键步骤。由于缺乏直接观测原子热振动的实验技术，振动归属通常通过经验试错法进行，存在相当大的不确定性。在此，我们展示了基于第一性原理分子动力学轨迹对分子固有振动性质的成功研究。开发了一种用于计算和归属振动频率的统一方法，并将其应用于解决苯振动的一些历史问题。作为一项主要成果，重新确定了苯a和b振动的实验频率，这打破了当代光谱科学中的僵局，并消除了密度泛函理论在有机化学应用中的阴霾。这项工作为全面实现第一性原理光谱研究铺平了道路，并为解决凯库勒共振、π变形和芳香性等百年问题提供了关键线索。
