Elastic Scattering of Slow Electrons by Two-Electron Ions

A one-channel model, previously used for He, is extended to allow calculation of elastic scattering by ${\mathrm{H}}^{-}$ and ${\mathrm{Li}}^{+}$ at energies up to 3 Ry. Nonseparable ground-state wave functions are used, allowance being made for exchange, and dipole and quadrupole polarization potentials. Results for ${\mathrm{Li}}^{+}$ are in good agreement with quantum-defect-method values. Calculated differential cross sections for elastic scattering by ${\mathrm{H}}^{-}$ at energies of ½ and 1 Ry are presented. Deviations from Couloumb scattering are marked. Phase shifts ($l=0, 1$) for higher members of the isoelectronic sequence ($4\le Z\le 10$) are given at threshold and 1 Ry.