Theoretical study of theP1doubly excited autoionization state of the magnesium atom

We present a theoretical study of the 3pns and 3pnd ${}^1$P doubly excited autoionization series above the first-ionization threshold of magnesium atom. The effect of the configuration interaction on the width and the energy position of the autoionization state is examined in detail. In particular, we have shown that the width of the narrow 3pnd ${}^1$P series is strongly affected by the configuration interaction. The results of the present calculation are also in good agreement with the existing theoretical and experimental data. In addition, the present theoretical approach is shown to be effective in the quantitative calculation for higher excited states in the autoionization series.