Terahertz phonon modes of an intermolecular network of hydrogen bonds in an anhydrous β-d-glucopyranose crystal

First-principles calculations of single molecular vibrations and the crystalline phonons of an anhydrous β-d-glucopyranose monosaccharide crystal in the terahertz region were performed using periodic density functional theory (DFT) calculations. The calculated frequencies and eigenvectors of the phonon modes, which agreed with experimental results, did not correspond to those of the modes of a single molecule, mainly due to intermolecular hydrogen bonds and molecular deformation in the crystal. In addition, the phonon modes derived from molecular translations or rotations were estimated for a wide range of 46.2–312.4 cm−1 by sampling the eigenvectors of the vibrational modes.