Hartree-fock stability and broken symmetry solutions of O2- and S2-anions in external confinement

We study the effect of a confining potential on systems that exhibit Hartree-Fock (HF) instabilities, and thus admit broken symmetry (BS) HF solutions, by relying on the O 2- and S 2- doubly-charged anions as model systems. We find that with the increasing strength of the external harmonic confinement potential, W ( r ) = 1/2( ωr ) 2 (with 0.0 ≤ ω W ( r ), we also examined a more realistic "confinement", realized by a grid of point charges modelling the crystal structure of MgO. Again, we find that the HF instabilities and the implied BS solutions disappear with the increasing magnitude of the model charges simulating the crystal environment. At the same time, the O 2- anion is energetically stabilized with respect to both the O - anion and the neutral oxygen atom.