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The structures of the 3s23p 'Po ground state and of a number of excited states for aluminum and ions along the isoelectronic sequence up to Ca VI11 have been calculated in the Multiconfiguration Optimized Potential Model. The excited states include the following: 3s23d '0, 3 ~~4 s 'S, 3s3p' 'D, 'S, as well as 3s24p, 3p3 and 3s3p('P0)3d 'Po. There is strong configuration mixing in the spectroscopic terms but on the basis of our calculations we recommend a different designation from that currently adopted for the 3p' and 3 ~3 p ( ~P ' ) 3 d 'Po terms. Oscillator strengths for transitions among these terms have been calculated in the length and velocity formulation with particular emphasis on accurate description in the vicinity of term crossings. Comparison is made with other theory and with experiment where results are available. At present, the experimental data are inadequate to verify the many calculated structures in the isoelectronic gf dependence.

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We have calculated oscillator strengths in the length and velocity formulation for a large number of transitions in the Aluminum isoelectronic sequence from Si II through K VII, using the Multiconfiguration Optimized Potential Model. The results have been used to determine the lifetimes of 14 low-lying excited terms along the sequence. Comparison is made with experiment and with other theory where results are available. The agreement between our values and other theoretical results is generally good, although deviations do occur near level crossings. Some significant discrepancies between theory and experiment persist concerning lifetimes for S IV.