Ab initio calculations on low-lying electronic states of SbO₂‾ and Franck-Condon simulation of its photodetachment spectrum

Abstract

Geometry optimization and harmonic vibrational frequency calculations have been carried out on the low-lying singlet and triplet electronic states of the antimony dioxide anion (SbO₂‾) employing a variety of ab initio methods. Both large-core and small-core relativistic effective core potentials were used for Sb in these calculations, together with valence basis sets of up to augmented correlation-consistent polarized-valence quintuple-zeta (aug-cc-pV5Z) quality. The ground electronic state of SbO₂‾ is determined to be the X˜¹ A₁state, with the ã³B₁state, calculated to be ~48 kcal mole⁻¹ (2.1 eV) higher in energy. Further calculations were performed on the X˜²A₁,A˜²B₂, and B˜²A₂states of SbO₂with the aim to simulating the photodetachment spectrum of SbO₂‾. Potential energy functions (PEFs) of the X˜¹ A₁state of SbO₂‾ and the X˜²A₁, A˜²B₂, and B˜²A₂states of SbO₂were computed at the complete-active-space self-consistent-field multireference internally contracted configuration interaction level with basis sets of augmented correlation-consistent polarized valence quadruple-zeta quality. Anharmonic vibrational wave functions obtained from these PEFs were used to compute Franck-Condon factors between the X˜¹ A₁ state of SbO₂‾ and the X˜²A₁, A˜²B₂, and B˜²A₂state of SbO₂, which were then used to simulate the photodetachment spectrum of SbO₂‾), which is yet to be recorded experimentally.