Energy of 1s2ns(n=3, 4, and 5) states for the lithium isoelectronic sequence

The nonrelativistic energies of the lithiumlike 1${\mathit{s}}^2$ns (n=3, 4, and 5) states for Z=3 to 10 are calculated by using a full-core-plus-correlation method with multiconfiguration-interaction wave functions. Relativistic and mass-polarization effects on the energy are evaluated as the first-order perturbation corrections. The quantum-electrodynamic (QED) correction to the energy is included using effective nuclear charge. Our results are compared with the experimental data in the literature. For Z<8 systems, the discrepancies are about 1 ${\mathrm{cm}}^{\mathrm{-}1}$ or less in most cases. Our nonrelativistic energies are also compared with previous theoretical results in the literature.