The hyperfine structure of the 1s2ns2S and 1s2np2P states (n =2,3,4, and 5) for the lithium isoelectronic sequence

The non-relativistic hyperfine structure parameters, the Fermi contact, the spin-dipolar, the orbital and the electronic quadrupole terms, of the lithium-like ground state and low-lying states, 1s2ns2S and 1s2np2P (n=2,3,4, and 5), are calculated with the full core plus correlation (FCPC) wave functions. With the 794- and 1185-term Slater-type expansions, the Fermi contact interactions of the 22S and 22P states in 7LiI are determined to be 2.90313 a.u. and -0.21359 a.u., respectively. By using the global identities, the Fermi contact term is also given for the ground state in LiI. The typical patterns of convergence of the expectation values of the Fermi contact interaction for the lithium 1s22s and 1s22p states are analyzed. The contribution from the core polarization is examined. The calculated results of the lithium-like systems from LiI to NeVIII are compared with the previous theoretical results obtained with other methods, and with the experimental data available in the literature. (orig.)