Effective-Field Calculations of Polarizabilities and Shielding Factors for He, Ne, A, and Kr Isoelectronic Series

Electronic dipole and quadrupole polarizabilities and the Sternheimer shielding or antishielding factors are calculated for several closed-shell atomic systems. The calculations are carried out by an effective-field method using the perturbed orbitals, given by the uncoupled Hartree---Fock method, as trial functions. The external field is replaced either by a mean effective field taking into account the mean coupling between the deformations of the various orbitals or by a set of effective fields, each of them being relative to a particular perturbed orbital. Numerical results obtained for the He, Ne, A, and Kr isoelectronic series show a much better agreement with the corresponding coupled values than the initial uncoupled results.