Many-Body Calculation of Atomic Polarizability -Relation to Hartree-Fock Theory

The Brueckner-Goldstone perturbation method has been applied to the calculation of the dipole polarizability (${\alpha }_d$) and antishielding factor (${\gamma }_d$) for lithium-atom ground state. The complete set of states utilized is the same as those employed in earlier calculations of the hyperfine constant and correlation energy. Our results are ${\alpha }_d=24.84\mathrm{}$ ${\mathrm{\AA }}^3$ and ${\gamma }_d=0.958\mathrm{}$, as compared to a recent experimental value for ${\alpha }_d=22\mathrm{}\pm 2$ ${\mathrm{\AA }}^3$ and ${\gamma }_d=1.000\mathrm{}$ from the Hellmann-Feynman theorem. The relationship between the Brueckner-Goldstone and the Hartree-Fock perturbation procedures is discussed with reference to specific physical effects.