Polarizability of helium and the negative hydrogen ion

We have carried out precision calculations of the dipole and quadrupole polarizabilities of helium and the negative hydrogen ion and their non-adiabatic extensions. These quantities are obtained from second-order perturbation sums involving energy denominators raised to the power k = 1, 2 or 3. The summation over intermediate states is carried out using Hylleraas two-particle wavefunctions of the appropriate symmetry and angular momentum. The measured mass of the nucleus is retained. The convergence is excellent for the helium case and somewhat poorer for H-. (author)