Theoretical calculation of energy levels and spectra <i>ab nitio</i> are described forinitio transitions of the type p<sup>m</sup>-p<sup>m-1</sup><i>l</i>, especially 3<i>p<sup>m</sup></i>-3<i>p</i><sup>m-1</sup>3<i>d</i> transitions in the Ar I and Cl I isoelectronic sequences. Strong changes of wvavefunction composition occur in going from neutral atoms to ions as a result of collapse of the 3<i>d</i> wavefunction; for <i>m</i> = 2 and 6 these take the form of coupling changes, and for <i>m</i> = 3-5 they take the form of changes of parentage composition. Abnormally low Ti v 3<i>p</i><sup>6</sup>-3<i>p</i><sup>5</sup>4<i>d</i> intensities are explained as an interference effect in evaluation of the dipole radial integral.
ROBERT D. COWAN, "Theoretical Study of pm-pm-1l Spectra," J. Opt. Soc. Am. 58, 924-932 (1968)