Lattice vibrations of ices Ih, VIII, and IX

摘要

We report the results of molecular dynamics calculations on ice Ih, and the proton ordered ices VIII and IX based on the SPC intermolecular potential, which was parametrized to the properties of liquid water. Particular emphasis is placed on the calculation of vibrational frequency spectra and comparison is made with incoherent inelastic neutron scattering data for ice Ih. The calculated longitudinal acoustic modes agree well with experiment but the transverse acoustic and optic modes are too soft, as are the librational modes. These conclusions are confirmed by comparing individual phonon frequencies for deuterated ice Ih with the measured phonon dispersion curves. Frequency spectra are presented for ice VIII and ice IX.