CCSD(T) calculations of stabilities and properties of confined systems

We analyze energies, electron affinities and polarizabilities of small anions exposed to an external confinement. The second electron in free O2− and S2− anions is unbound. We investigate the stabilizing effect of the spherical harmonic-oscillator confining potential ω. on these anions employing the Hartree-Fock stability analysis as introduced by Cižek and Paldus. With increasing strength of the external harmonic-oscillator confinement potential ω the broken symmetry (BS) solutions are systematically eliminated. For ω larger than 0.1 all BS solutions for O2− disappear. For ω larger than 0.13 the CCSD(T) energy of O2− becomes more negative than the energy of the singly charged O− anion. We relate the harmonic-oscillator confining potential to a crystalline environment in which the O2− and S2− anions are stable. We also present a model allowing calculations of the in-crystal polarizabilities of anions. The model is based on CCSD(T) calculations of static polarizabilities of selected anions exposed to the s...