分子動力学法を用いたカーボンナノチューブへの閉じ込めによる水分子の振動スペクトル変化の解析

抄録

Water confined in nano-space show peculiar features which do not appear in bulk system. Carbon nanotubes (CNTs) are promising materials as nano pore due to their uniform structures and rich variation. The behavior of water confined in CNT has been studied to apply the features to engineering. Recently, a peculiar peak was observed in the spectra of water confined in CNT by infrared spectroscopy, which does not appear in the spectra of bulk systems. While molecular simulation is a useful method to study nano-scale phenomena, it still proved to be insufficient to identify the mechanism, because it is impossible to simulate anharmonic vibrations of water molecules using ordinal harmonic potentials. In this study, molecular dynamics simulation with modified water model that generates anharmonic vibration was carried out and the relationship between vibrational frequencies and the distributions of water molecules inside CNT was analyzed. The high vibrational frequencies that correspond to the peculiar peak were confirmed from water molecules located near the carbon atoms of CNT.