Vibrational polarizabilities of hydrogen-bonded water

Abstract

The vibrational polarizabilities and the related molecular properties of hydrogen-bonded water are analyzed theoretically, taking the case of (water)30 clusters as an example case. It is shown that some off-diagonal dipole derivatives are large for the translations of incompletely hydrogen-bonded molecules, and this is reasonably explained by the scheme of intermolecular charge fluxes induced along hydrogen bonds. In total, because of these intermolecular charge fluxes, molecular translations give rise to the vibrational polarizability of 2.8–3.3 a03 per molecule, which is as large as about 40% of the electronic polarizability, mainly in the frequency region below 300cm−1. Adding the contributions of the molecular rotations (librations) and the translation–rotation cross term, the total polarizability (electronic+vibrational) at ∼100cm−1 is slightly larger than the double of that at >4000cm−1. The relation of these results to some observed time- and frequency-dependent dielectric properties of liquid water is briefly discussed.