title: Characteristics of Low-Frequency Molecular Phonon Modes Studied by THz Spectroscopy and Solid-State ab Initio Theory: Polymorphs I and III of Diflunisal.
abstract: THz absorption spectra of two polymorphs of diflunisal, form I and form III, exhibit distinct features due to the influence of packing conformations on the frequency distributions and IR activities of gamma point phonon modes within the 100 cm(-1) region. In order to understand the origins of these THz modes, we perform a detailed mode analysis. The result shows that although the spectral features are different, these low-frequency phonon modes of the two molecular polymorphs have similar vibrational characteristics in terms of harmonic couplings of intermolecular and intramolecular vibrations.
authors.affiliation: Molecular Photoscience Research Center, Kobe University , Kobe 657-8501, Japan.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University , 1 Roosevelt Road Sec. 4, Taipei 10617, Taiwan.
authors.forename: Houng-Wei
authors.initials: HW
authors.lastname: Wang
authors.affiliation: Molecular Photoscience Research Center, Kobe University , Kobe 657-8501, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tominaga
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University , 1 Roosevelt Road Sec. 4, Taipei 10617, Taiwan.
authors.forename: Michitoshi
authors.initials: M
authors.lastname: Hayashi