PHOTOIONIZATION OF MAGNESIUM INCLUDING DOUBLE EXCITATIONS

The multiconfiguration relativistic random-phase approximation is appl ied to the photoionization of magnesium. Autoionization resonances bet ween the 3s1/2 and 3p1/2 ionization thresholds are investigated. The m ain feature of our results is exhibited by three Rydberg series: the b road 3pns P-1(1) series, the narrow 3pnd P-1(1) series, and the 3pns P -3(1) series caused by the fine-structure splittings. Our predictions of the resonance positions are in excellent agreement with experiment, and are consistent with other calculations. For photon energies above the 3p3/2 threshold, cross sections and spin polarizations of photoel ectrons from the ionization channels Mg --> Mg+(S-2(1/2))+e-, Mg --> M g+(P-2(1/2)0)+e-, and Mg --> Mg+(P-2(3/2)0)+e- are obtained and compar ed with other theoretical results.