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Symmetry breaking and electron correlation in O2−, O2, and O2+: A comparison of coupled cluster and quadratic configuration interaction approaches

✍ Scribed by Charu A. Chandrasekher; K. S. Griffith; Gregory I. Gellene

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
837 KB
Volume
58
Category
Article
ISSN
0020-7608

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✦ Synopsis

Potential energy curves are calculated for O;, 0,, and 0: at the CCSD, QCISD, CCSD(T), and QCISD(T) levels of theory using aug-cc-pVDZ and aug-cc-pVTZ basis sets with electron correlation built onto inversion symmetry constrained and relaxed UHF wave functions. The spectroscopic constant Y,, we, w,x,, D,, and a, are determined from the potential curves using standard second-order perturbation theory expressions and are compared with experimental values to assess the relative accuracy of the theoretical approaches. Comparison of corresponding symmetry-constrained and symmetry-relaxed calculations indicates that the CCSD method is generally superior to CCSNT), QCISD, and QCISD(T) in recovering from a symmetry-broken reference function.

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