Frequency-dependent multipole polarizabilities. II. Application of a reduced Green’s function formulation of TDHF theory to the helium isoelectronic sequence

Abstract

A reduced Green’s function formulation of time-dependent Hartree–Fock theory is developed using diagrammatic techniques. The resulting integral equations are transformed using a power moment approach. An asymptotic ansatz of the form exp{−[−2(εi ∓ω)]1/2r}am† polynomial is used to fit the radial functions φ±l(r). From these functions, the frequency-dependent dipole, quadrupole, and octapole polarizabilities of the helium isoelectronic sequence for Z=2–10 are calculated. Results are reported for the static case. It is found that the poles of the polarizabilities which correspond to TDHF excitation energies from the ground state can be accurately determined for highly excited states. These excitation energies are reported and are related to a Rydberg formula. The resulting quantum defects are also reported.