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A terahertz study of taurine: Dispersion correction and mode couplings

The low-frequency characteristics of polycrystalline taurine were studied experimentally by terahertz (THz) absorption spectroscopy and theoretically by ab initio density-functional simulations. Full optimizations with semi-empirical dispersion correction were performed in spectral computations and...

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Bibliographic Details
Published in:The Journal of chemical physics 2017-03, Vol.146 (12), p.124119-124119
Main Authors: Dai, Zelin, Xu, Xiangdong, Gu, Yu, Li, Xinrong, Wang, Fu, Lian, Yuxiang, Fan, Kai, Cheng, Xiaomeng, Chen, Zhegeng, Sun, Minghui, Jiang, Yadong, Yang, Chun, Xu, Jimmy
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Language:English
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Summary:The low-frequency characteristics of polycrystalline taurine were studied experimentally by terahertz (THz) absorption spectroscopy and theoretically by ab initio density-functional simulations. Full optimizations with semi-empirical dispersion correction were performed in spectral computations and vibrational mode assignments. For comparison, partial optimizations with pure density functional theory were conducted in parallel. Results indicate that adding long-range dispersion correction to the standard DFT better reproduces the measured THz spectra than the popular partial optimizations. The main origins of the observed absorption features were also identified. Moreover, a coupled-oscillators model was proposed to explain the experimental observation of the unusual spectral blue-shift with the increase of temperature. Such coupled-oscillators model not only provides insights into the temperature dynamics of non-bonded interactions but also offers an opportunity to better understand the physical mechanisms behind the unusual THz spectral behaviors in taurine. Particularly, the simulation approach and novel coupled-oscillators model presented in this work are applicable to analyze the THz spectra of other molecular systems.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4978896