Electronic structure and spectroscopy of carbon trioxide

Carbon trioxide plays an important role in atmospheric chemistry and has been detected in interstellar ices. However, its ground state symmetry has eluded both experimental and computational chemists for decades.

We are using coupled cluster methods to acquire a more thorough understanding of the electronic structure of carbon trioxide.

Carbon trioxide geometries

Cs, D3h, and C2v isomers of carbon trioxide. All three structures have been previously proposed for the ground state of the molecule

By calculating equilibrium geometries with coupled cluster methods, we determined that the C2v isomer is the global energy minimum, with the D3h structure approximately 3 kcal/mol higher in energy. Moreover, the shape of the ground state potential energy surface along the C2v distortion is strongly affected by the vibronic coupling with the low-lying excited states. The Jahn-Teller distortions of the excited states enhance the vibronic couplings.

Ground state

Relevant molecular orbitals and the ground-state electronic configuration of CO3 at C2v (left) and D3h (right) geometries.

Excited states

Electronically excited states of the C2v (upper panel) and D3h (lower panel) isomers of CO3.

Carbon trioxide will be investigated in the laboratory of our experimental collaborator, Dr. Mitchio Okumura (Caltech). The computational results will be used in determining the appropriate experimental setup for the upcoming study.

Related Publications

56. T. Kowalczyk and A. I. Krylov
Electronic structure of carbon trioxide and vibronic interactions involving Jahn-Teller states
J. Phys. Chem. A 111, 8271 – 8276 (2007) Abstract  PDF (87 kB)