Quartet spectra in three-electron atoms

Routine calculations have been performed on the quartet terms of configurations 1s2snl and 1s2pnl, n=2, 3, 4, 5; l=0, 1, 2, 3 for the isoelectronic series Li-Ne+7 in the one-configuration approximation by direct minimization. The conditions for orthogonality between wave functions identical in symmetry are provided by the frozen excited core approximation. The errors of this approximation are examined, and it is shown that the results are quite satisfactory for qualitative analysis of quartet spectra in the z sequence. A study is made of the changes in relative position of the levels as the nuclear charge alters; the intersection of terms identical in symmetry as functions of z is discussed. The z dependence of the allowed transitions is examined.