ATOMIC-STRUCTURE CALCULATIONS INVOLVING OPTIMIZATION OF RADIAL INTEGRALS - ENERGY-LEVELS AND OSCILLATOR-STRENGTHS FOR FE-XII AND FE-XIII 3P-3D AND 3S-3P TRANSITIONS

Energy levels and oscillator strengths are calculated for the 3s2 3pq-3s2 3pq-1 3d and 3s23pq-3s 3pq+1 transition arrays of Fe XII and Fe XIII. Strong configuration interactions are explicitly included in the computations, and the method also involves adjustment of radial energy-integrals Fk, Gk, Rk, in order to minimize differences between observed and calculated energy levels, under the least-squares criterion. It is found that Fk, Gk, Rk integrals need to be reduced from ab init. values (by over 30 per cent for some of the configuration-mixing integrals for Fe XII) and this substantially affects some oscillator strengths. Several spectral lines are newly classified as a result of this analysis.The possible use of empirically adjusted radial-integral values in electron-ion collisional-excitation calculations (as a means of improving the accuracy of target wavefunctions) is discussed. © 1978 Royal Astronomical Society. Provided by the NASA Astrophysics Data System.