P-4(0) SERIES OF LITHIUM

The term energies of the lowest ten doubly excited 4P-degrees terms of neutral lithium are calculated by using the restricted variational me thod with a full core plus correlation. Relativistic and mass-polariza tion effects are included as the first-order perturbation to the nonre lativistic energy. Our results support the assignments for the observe d lines at 3619 angstrom and at 4885 A as the decay from the term 1s2p 3s 4P-degrees. This term is identified as the seventh member in the -4 P-degrees series, and its energy is almost degenerate with that of the eighth member, being only 24 cm-1 apart. To facilitate unambiguous cl osed loop analyses in comparisons with experiment, precision calculati ons are also carried out to determine the relative term values for 1s2 p2p 4P at 26 915.7(5) cm-1 and for 1s82s3d 4D at 42 778.4(4) cm-1, whi ch agree well with the experimental data of 26 915.16(6) cm-1 and 4277 8.3 cm-1, respectively. Our results suggest that the transition 1s2s3d 4D - 1s2p3s4P-degrees should be at 8500.5 angstrom.