• Cluster expansion of the wave function. Potential energy curves of the ground and excited states of CO

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      https://www.ias.ac.in/article/fulltext/jcsc/096/03-04/0155-0166

    • Keywords

       

      Symmetry-adapted-cluster theory; symmetry-adapted-cluster-configurational-interaction theory; Rydberg and valence excited states; Thouless theorem; non-variational method; coupled-cluster-many-electron theory; quasi-degenerate correlation; Dunham theory; Rydberg and valence transitions

    • Abstract

       

      Thesac (symmetry-adapted cluster) andsac-ci (sac-configurational interactions) theories have been applied to the calculations of the potential curves of the ground and excited states of the CO molecule. The states studied are valence typeX1Σ+, (4)1Σ+,A2Π,I1Σ,D1Δ,a3Π,a3Σ+,d3Δ, ande3Σ−1, and of Rydberg typeB1Σ+,C1Σ+, andF1Σ+. For the description of theX1Σ+ and (4)1Σ+ states, we took advantage of the fact that thesac andsac-ci solutions satisfy orthogonality and Hamiltonian orthogonality to each other. Near the avoided crossing region of these states, however, thesac theory fails because of the multi-reference nature of the correlation. Our theoretical potential curves of the ground and various excited states are very similar to therkr (Rydberg-Klein-Rees) potential curves based on experimental data. The spectroscopic constants calculated also agree well with experimental values.

    • Author Affiliations

       

      O Kitao1 H Nakatsuji1

      1. Division of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto - 606, Japan
    • Dates

       
  • Journal of Chemical Sciences | News

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