Dipole polarizability of the fluoride ion with many-body methods

The dipole polarizability of ${\mathrm{F}}^{-}$ and the electron affinity of F are studied using full fourth-order many-body perturbation theory (MBPT) and the infinite-order coupled-cluster single- and double-excitation model (CCSD). It is shown that the fourth-order correlation corrections for the polarizability of ${\mathrm{F}}^{-}$ are larger than second-order, raising questions about the suitability of finite-order methods for including electron correlation effects on the polarizability of this system. MBPT-CC results in a variety of basis sets suggest that the experimentally unknown polarizability of ${\mathrm{F}}^{-}$ is ∼ 18-20 a.u., of which a large percentage is due to the inclusion of triple-excitation effects.