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Proceedings Paper

Low-frequency vibration study of amino acids using terahertz spectroscopy and solid-state density functional theory
Author(s): Feng Zhang; Keisuke Tominaga; Michitoshi Hayashi; Houng-Wei Wang
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Paper Abstract

Understanding the low-frequency normal modes of amino acids, the building blocks of proteins, is crucial to reveal the vibration-function relationship in the macromolecular system. Recent advances in terahertz spectroscopy (THz) and solid-state density functional theory (DFT) have ensured an accurate description of low-frequency modes of amino acids. New knowledge people have learnt so far is that the inter- and intra-molecular vibrations are strongly mixed with each other in the THz region through the vibrational coordinate mixing. Rich information is believed embedded in this phenomenon. We introduce a generalized mode-analysis method that allows for the accurate decomposition of a normal mode of interest into the three intermolecular translations, three principal librations and various intrinsic intramolecular vibrations. This mode-analysis method will be demonstrated in the crystalline C60 systems and then applied to shed light on the nature of low-frequency phonons of glycine, diglycine and triglycine. This method helps reveal new intramolecular vibrational modes on the first hand, and more importantly, illuminate a new phenomenon of the frequency distribution of intramolecular vibrations (FDIV). FDIV describes the possible broad distributions of important intramolecular vibrations in the low-frequency normal modes. The FDIV concept may indicate an additional mechanism for the intramolecular vibrations to become thermally active and participate in various biological functions.

Paper Details

Date Published: 11 November 2014
PDF: 9 pages
Proc. SPIE 9275, Infrared, Millimeter-Wave, and Terahertz Technologies III, 92750D (11 November 2014); doi: 10.1117/12.2071528
Show Author Affiliations
Feng Zhang, Kobe Univ. (Japan)
Keisuke Tominaga, Kobe Univ. (Japan)
Michitoshi Hayashi, National Taiwan Univ. (Taiwan)
Houng-Wei Wang, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 9275:
Infrared, Millimeter-Wave, and Terahertz Technologies III
Cunlin Zhang; Xi-Cheng Zhang; Masahiko Tani, Editor(s)

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