The vibrating hydroxide ion in water

Kersti Hermansson, Philippe A. Bopp, Daniel Spngberg, Ljupco Pejov, Imre Bakó, Pavlin D. Mitev

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The OH- ion in water is studied using a CPMD/BLYP + QM electronic + QMvibrational approach. The ion resides in a cage of water molecules, which are H-bonded among each other, and pinned by H-bonding to the ion's O atom. The water network keeps the 'on-top' water in place, despite the fact that this particular ion-water pair interaction is non-binding. The calculated OH- vibrational peak maximum is at ∼3645 cm-1 (experiment ∼3625 cm-1) and the shift with respect to the gas-phase is ∼ +90 cm-1 (experiment +70 cm-1). The waters molecules on each side of the ion (O and H) induce a substantial OH- vibrational blueshift, but the net effect is much smaller than the sum. A parabolic 'frequency-field' relation qualitatively explains this non-additivity. The calculated 'in-liquid' ν(OH-) anharmonicity is 85 cm-1.

Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalChemical Physics Letters
Issue number1-3
Publication statusPublished - Sep 27 2011


ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Hermansson, K., Bopp, P. A., Spngberg, D., Pejov, L., Bakó, I., & Mitev, P. D. (2011). The vibrating hydroxide ion in water. Chemical Physics Letters, 514(1-3), 1-15.