The C̃ 2A2 excited state of NO2: Evidence for a Cs equilibrium structure and a failure of some spin-restricted reference wavefunctions

T. Daniel Crawford, John F. Stanton, P. Szalay, Henry F. Schaefer

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The geometry and harmonic vibrational frequencies of the the C̃ 2A2 electronic state of nitrogen dioxide have been determined using coupled cluster (CC) theory in conjunction with large basis sets. The minimum energy C-constrained N-O bond distance predicted by the highest level of theory is significantly shorter than the experimentally inferred value, and it is unlikely that further refinement in the theoretical treatment would reduce the discrepancy. However, this work suggests that a prevailing assumption of C, symmetry may be incorrect; the equilibrium structure of the C state may instead have Cs symmetry. In addition, and contrary to expectation, CC calculations based on variationally optimal spin-unrestricted or spin-restricted reference determinants give qualitatively different results for this system, unless very high levels of electron correlation are included in the calculation.

Original languageEnglish
Pages (from-to)2525-2528
Number of pages4
JournalThe Journal of Chemical Physics
Volume107
Issue number7
Publication statusPublished - Aug 15 1997

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Wave functions
Excited states
Nitrogen Dioxide
Electron correlations
nitrogen dioxide
Electronic states
symmetry
Vibrational spectra
determinants
excitation
harmonics
Geometry
geometry
electronics
electrons
energy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

The C̃ 2A2 excited state of NO2 : Evidence for a Cs equilibrium structure and a failure of some spin-restricted reference wavefunctions. / Crawford, T. Daniel; Stanton, John F.; Szalay, P.; Schaefer, Henry F.

In: The Journal of Chemical Physics, Vol. 107, No. 7, 15.08.1997, p. 2525-2528.

Research output: Contribution to journalArticle

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