Energies of Doubly Excited <sup>1,3</sup>P° Resonances in He-like Systems Below the N = 2–14 Hydrogenic Threshold

In this present work, resonance energies and excitation energies of doubly 1,3P° excited states of the helium isoelectronic sequence are calculated. The doubly excited states investigated are labelled in the (K, T, A) classification scheme. The energies are calculated in the framework of the variationnal procedure of the Screening constant by unit nuclear charge (SCUNC) formalism. The results obtained compared very well with theoretical and experimental literature values. The possibility to use the SCUNC formalism report rapidly with an excellent accuracy the position of the excitation resonances as well as their width within simple analytical formulae is demonstrated. It is demonstrated that the SCUNC-method can be used to assist fruitfully experiments for identifying narrow resonance energies. Thus, our results can be used as reference data for the interpretation of atomic spectra for the diagnosis of astrophysical and laboratory plasma. In the present work, a new correlated wave function is presented to express analytically the resonance energies and excitation energies of doubly 1,3P° excited states in the He-like systems.