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Mode assignments for THz vibrational spectra of molecular crystals


Topic: Mode assignments for THz vibrational spectra of molecular crystals
Speaker: Dr. Feng Zhang, Kobe University, Japan
Time: Friday, December 22, 2017, 14:00 P M
Location: Room 528, Chemistry Building A
Inviter: Prof. Dongping Zhong 
Terahertz (THz) spectroscopic measurement of molecular crystals have become a routine practice in many laboratories, but the interpretation of the measured peaks is far from routine.


We will introduce our progresses in the past decade in solving one of the basic problems—mode assignment—through the interplay of THz spectroscopy and solid-state ab initio theory. Quantitative agreements between experiment and theory have been achieved for a broad spectrum of prototypical molecular systems.


A quantitative mode analysis method has been established for characterizing the origin of any THz mode of interest. 


On this basis, we will illustrate the power of THz spectroscopy in tackling some major problems of X-ray crystallography. Two examples will be specifically elucidated. One is the determination of the positions of hydrogen atoms in polymer crystals; the other is the deduction of the packing information in disordered molecular crystals.


We will finally outlook the applications of THz spectroscopy to revealing the structure-encoded vibrations of proteins and to studying anharmonicity of molecular phonon modes. 
Feng Zhang received a B. Eng. and M. Eng. from Nanjing Forestry University (2005) and Kunming University of Science and Technology (2008), China, respectively. He joined the Tominaga group in Kobe University, Japan in 2009, and earned a D. Sc. in 2013. He has since worked as a postdoctoral researcher in the Tominaga group.


His research interest is exploring the low-frequency vibrations in molecular systems and quantifying their relations with many macroscopic properties of materials through the interplay of the experimental and theoretical approaches.