New approach to hyperfine structure - Application to the Li ground state

Global identities for delta functions, given by Hiller, Sucher and Feinberg (HSF) are applied to the calculation of the hyperfine structure (HFS) of the ground state of Li. It is shown that use of the HSF identity together with configuration interaction type wavefunctions can yield values of the HFS constant f which are comparable in accuracy to that obtained by Larsson with a 100-term Hylleraas-type wavefunction. The implications of this result for HFS calculations for atoms with many electrons are discussed.