ENERGY OF 1S2NS (N = 3, 4, AND 5) STATES FOR THE LITHIUM ISOELECTRONIC SEQUENCE

The nonrelativistic energies of the lithiumlike 1s2ns (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 cm-1 or less in most cases. Our nonrelativistic energies are also compared with previous theoretical results in the literature.