Symmetry breaking in O+4: an application of the Brueckner coupled-cluster method
1994 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 223, no 3, 207-214 p.Article in journal (Refereed) Published
A recent calculation of the antisymmetric stretch frequency for the rectangular structure of quartet O4+ using the QCISD(T) method gave a value of 3710 cin-1. This anomalous frequency is shown to be a consequence of symmetry-breaking effects, which occur even though the QCISD(T) solution derived from a delocalized SCF reference function lies energetically well below the two localized (symmetry-broken) solutions at the equilibrium geometry. The symmetry breaking is almost eliminated at the CCSD level of theory, but the small remaining symmetry-breaking effects are magnified at the CCSD (T) level of theory so that the antisymmetric stretch frequency is still significantly in error. The Brueckner coupled-cluster method, however, leads to a symmetrical solution which is free of symmetry-breaking effects, with an antisymmetric stretch frequency of 1322 cm-1, in good agreement with our earlier calculations using the CASSCF/CASSI method.
Place, publisher, year, edition, pages
1994. Vol. 223, no 3, 207-214 p.
IdentifiersURN: urn:nbn:se:uu:diva-143939DOI: 10.1016/0009-2614(94)00442-0ISI: A1994NQ82500013OAI: oai:DiVA.org:uu-143939DiVA: diva2:394327