4 Conclusions

In this paper we have reported values of oscillator strengths and radiative rates for transitions among the (1s²) 2s²2p², 2s2p³, 2p⁴, 2s²2p3s, 2s²2p3p and 2s²2p3d configurations of C-like K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX. Relativistic effects as well as elaborate CI have been included in the calculations. The results have been compared with the earlier available values obtained by Fawcett (1987) from the HFR code of Cowan (1981).

The energy levels agree to better than 3% with the experimental compilations, but the levels ordering are slightly different in a few instances. Furthermore, experimental energies for all the levels are not available, and the deficiency is greater for the higher levels, in particular. This may result in an incorrect order of some of the levels, leaving scope for future amendments.

The oscillator strengths for transitions among the [1s²] 2s²2p², 2s³ and 2p⁴ configurations have been calculated by many workers, and have been compared and discussed in detail in the literature. However, similar calculations including the levels of the 2s²2p3$\ell$ configurations are rather limited, and radiative rates are available for a few transitions only. Therefore, the present calculations have reported values of oscillator strengths and radiative rates for all allowed transitions among 46 levels of the above six configurations, as well as improving the accuracy of the earlier work. The differences with the earlier calculations are generally within 30%, and the accuracy of our present calculations may not be better than 20%, especially for those transitions whose f-values are large ($\ge$0.1). For weaker transitions having smaller f-values, the corresponding accuracy estimate may be much lower.

Acknowledgements

The work reported in this paper has been financed by the EPSRC and PPARC of the United Kingdom, the National Science Foundation and Division of Chemical Sciences, Office of Basic Energy Sciences, DoE of the United States, and NATO grant CRG 930722.