Theoretical analysis toward better description of the wavenumber shifts of the OH stretch of hydrogen-bonded water

Relating vibrational properties to intermolecular configurations is generally important for correct analysis and interpretation of infrared and Raman spectra of condensed-phase systems. Here, a theoretical analysis in this direction is conducted through calculations on (water)(90) clusters for better description of the OH stretch of hydrogen-bonded water. It is shown that, while the electric field descriptor related to the vibrating OH bond primarily describes the wavenumber shift arising from hydrogen-bond formation, the secondary descriptors related to the other OH bond in the same water molecule noticeably improve the performance of theoretical modeling. It is also shown that, for the electric field descriptor, the electric charge configuration is an important factor for good performance. Explicit forms of those descriptors are presented that may be applicable to spectral simulations through combination with classical molecular dynamics. The mechanism behind the secondary descriptors is also discussed.

Automated summary

Relating vibrational properties to intermolecular configurations is crucial for accurate analysis and interpretation of spectra in condensed-phase systems. Through theoretical calculations on hydrogen-bonded water clusters, it is found that secondary descriptors related to the other OH bonds in the same water molecule significantly improve the performance of theoretical modeling, in addition to the primary descriptor related to the vibrating OH bond. The electric charge configuration is shown to be an important factor for good performance of the electric field descriptor.