Two basic vibrational modes of hydrogen bonds in ice XIII

Using a first-principles density functional theory method, we calculated the vibrational spectrum of ice XIII. In combination with spectroscopic experiments, we demonstrated that the two characteristic hydrogen bond (H-bond) peaks in the translational region of ice V (the hydrogen-disordered counterpart of ice XIII) recorded by inelastic neutron scattering originate from two basic H-bond vibrational modes. We first observed this phenomenon when studying ice Ic and then confirmed it when studying ice XIV, XVI, and XVII. This study of high-pressure ice XIII supports our theory that two basic H-bond modes exist as a general rule among the ice family. The “isolated O–H vibration modes” found by Whale et al. when studying ice XV are also discussed in this work.