The complex susceptibility of liquid water as a two-potential system of reorienting polar molecules

The theory, elaborated in previous works is applid to the calculation of liquid water wideband (0 < ν/cm−1 < 1000) dielectric spectra. These comprise the Debye relaxation region at the centimeter/millimeter wavelengths and the two-humped absorption coefficient frequency dependence in the far infrared (FIR) region. It is supposed that a major part of the H2O molecules, called [L]-particles or [L]-molecules, are bonded by relatively strong H-bonds; [L]-molecules perform librations of relatively small amplitude β (β is about 20°). The remaining molecules, called [R]-molecules, have more rotational/translational mobility. A new microscopic molecular confined rotator/double well potential model of liquid water is developed. The contributions of [L]- and [R]-molecules to the complex permittivity ε are found on the basis of the confined rotator (CR) and the double well potential (DWP) models, with rectangular and cos2 intermolecular potential profiles, respectively. It is shown that the CR/DWP model gives a good description of the Debye relaxation and a qualitative description of the FIR dielectric spectra of water