Ab initio investigations on the CaO2+ dication

•The CaO2+ dication reveals thermochemically stable low-lying electronic states.•The stable states are associated with Ca2+ + O dissociation limits.•The spin-orbit coupling terms of the triplet states have been calculated.•The vibronic energy levels have been determined for the triplet states.

The low-lying electronic states of the CaO2+ dication are investigated using high level ab initio calculations. The electronic states converging to the first and third dissociation limits are found to be thermochemically stable, with dissociation energies ranging from 0.17 eV to 0.83 eV. The electronic ground state is of 3Σ- nature and the adiabatic double ionization energy of CaO is computed at 21.16 eV. The main spectroscopic constants of the five low-lying bound electronic states of CaO2+ are reported. The spin-orbit coupling terms related to the X3Σ- and A3Π states are computed and used to calculate the vibronic levels of these states.

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