Ab initio treatment of gas phase GeO²⁺ doubly charged ion

Highlights: • Theoretical investigation of the novel gas-phase molecular species GeO²⁺. • Spectroscopic parameters of this dication in its electronic ground and exited states. • Theoretical double ionization spectrum of GeO. - Abstract: Using multi reference configuration interaction methodology in connection with a large basis set, we show that GeO²⁺ is a metastable species either in the ground or in the electronically excited states. This confirms the observation of this dication in gas phase by mass spectrometry. In addition, we derived a set of accurate spectroscopic terms for GeO²⁺ bound states. At the MRCI/aug-cc-pV5Z level of theory, the adiabatic double ionization energy of GeO is computed to be ∼28.93 eV