Correlation effects in low-energy scattering of electron by a model negative ion

This paper presents the results of first-order Bethe-Goldstone (BG) calculations of electron scattering from a two-electron model of a negative ion. The results of the BG calculations are compared to those obtained using several approximate polarisation potentials. The BG calculations appear to contain significant contributions from dynamical effects that are not incorporated in a formulation based on adiabatic (static) polarisation potentials, but that can be represented at least partially if the polarisability is treated as a frequency-dependent function. (author)