Vibrational energy levels of water

A. Császár, Ian M. Mills

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Several quartic force fields and a full sextic anharmonic force field for H2O have been determined from high-quality ab initio calculations, the highest at the aug-cc-pVQZ CCSD(T) level of theory. These force fields have been used to determine vibrational excited state band origins up to 15,000 cm-1 above the zero-point level, using both a perturbation-resonance approach and a variational approach. An optimised quartic force field has been obtained by least squares refinement of our best ab initio results to fit the observed overtone levels of 5 symmetrically substituted isotopomers of water (H16 2O, H17 2O, H18 2O, D2O, and T2O) with an rms error of less than 10 cm-1, using the perturbation-resonance model for the vibrational calculation. Predicate least squares refinement was used to provide a loose constraint of the refined force field to the ab initio results. The results obtained prove the viability of the perturbation-resonance model for use in larger molecular systems and also highlight some of its weaknesses.

Original languageEnglish
Pages (from-to)1101-1122
Number of pages22
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume53
Issue number8
Publication statusPublished - Jul 30 1997

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Electron energy levels
field theory (physics)
energy levels
Water
water
perturbation
Excited states
viability
harmonics
excitation

Keywords

  • Anharmonic force field
  • Perturbation-resonance model
  • Vibrational energy

ASJC Scopus subject areas

  • Spectroscopy

Cite this

Vibrational energy levels of water. / Császár, A.; Mills, Ian M.

In: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, Vol. 53, No. 8, 30.07.1997, p. 1101-1122.

Research output: Contribution to journalArticle

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