Molecular-model-based calculation of the complex permittivity of ice

The far-IR spectra of the complex permittivity and absorption of ice are analytically calculated with a two-fraction model. It is demonstrated that the hat potential can be used to describe the librational band adjacent to the IR region and related to the anharmonic rotation of dipoles in defects of the structure of ice. A specific dielectric response at a wave number of about 200 cm−1 is assumed to be caused by elastic vibrations of H2O molecules in the H-bond direction and their reorientation relative to this bond. This response is represented as two Lorentzian lines. Far-IR spectra of ice are calculated at temperatures of −7°C and 100 K and are compared with the wideband spectra of liquid water.