Prediction of the terahertz absorption features with a straightforward molecular dynamics method

Xiangyu Dai; Shuting Fan; Zhengfang Qian; Renheng Wang; Vincent P Wallace; Yiwen Sun

doi:10.1016/j.saa.2020.118330

Prediction of the terahertz absorption features with a straightforward molecular dynamics method

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Aug 5:236:118330. doi: 10.1016/j.saa.2020.118330. Epub 2020 Apr 14.

Authors

Xiangyu Dai¹, Shuting Fan¹, Zhengfang Qian², Renheng Wang³, Vincent P Wallace⁴, Yiwen Sun⁵

Affiliations

¹ College of Physics and Optoelectronic Engineering, Shenzhen University, 3688 Nanhai Road, Shenzhen 518060, Guangdong, China.
² College of Physics and Optoelectronic Engineering, Shenzhen University, 3688 Nanhai Road, Shenzhen 518060, Guangdong, China. Electronic address: zq001@szu.edu.cn.
³ College of Physics and Optoelectronic Engineering, Shenzhen University, 3688 Nanhai Road, Shenzhen 518060, Guangdong, China. Electronic address: wangrh@szu.edu.cn.
⁴ Dept of Physics, The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia.
⁵ National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518060, China. Electronic address: ywsun@szu.edu.cn.

PMID: 32330823
DOI: 10.1016/j.saa.2020.118330

Abstract

In this paper, we provide a straightforward method to predict the terahertz absorption spectrum based on a fixed charge model with classic molecular dynamics calculations. The absorption features in the frequency range between 1 and 3.4 THz of stearic acid B-form and between 1 and 2.7 THz of C-form were successfully calculated. Most of the absorption peaks from the simulation correspond well with those from the measurements. By calculating the spatial and time-dependent energy accumulation in the molecular system, the core idea of our calculation method is further validated. Compared with the ab initio calculations, our method provides a computationally inexpensive way to accurately predict the locations of absorption features. With regard to the traditional molecular dynamic simulations, our method is able to extract the spatial distribution of the energy accumulation as well as the local motions in the molecular system.