Magnetic hyperfine structure of lithium

For the first time a spin-polarized extended Hartree-Fock calculation on a three-electron system, Li, is reported. The calculations are discussed with primary emphasis on the hyperfine splitting spectrum which is determined by the spin density at the nucleus, Q(0)=|isz(i)(ri)|S. We calculate Q(0) for the ground state to be 0.2403, as compared with the experimental value of 0.2313.