第一原理計算による有機結晶のテラヘルツ格子振動

抄録

First-principles calculations of single molecular vibrations and crystalline phonons of β-D-glucopyranose, lactose, and 4'-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) in the region of terahertz (THz) frequency were performed by using periodic density functional theory calculations. Theoretical frequencies of phonon modes corresponded to central frequencies of experimental absorption bands in THz region, mainly due to intermolecular hydrogen bonds and intramolecular deformations in crystal. Moreover, phonon modes originating from molecular translations or rotations were estimated in a much wide range. This review of theoretical calculations of THz vibrational modes presents a remarkable influence of intermolecular hydrogen-bonded network on THz phonon modes of molecular crystals, and a cause of spectral variations between DAST derivatives by sampling eigenvectors of vibrational modes and force constants.