Doubly excited 2s2p 1,3P1 resonances in photoionization of helium

The multi-configuration Dirac--Fock (MCDF) method is implemented to study doubly excited 2s2p ^1,3P₁ resonances of the helium atom and the interference between photoionization and photoexcitation autoionization processes. In order to reproduce the total photoionization sprectra, the excited energies from the ground 1s² \¹S₀ state to the doubly excited 2s2p ^1,3P₁ states and the relevant Auger decay rates and widths are calculated in detail. Furthermore, the interference profile determined by the so-called Fano parameters q and ρ ² is also reproduced. Good agreement is found between the present results and other available theoretical and experimental results. This indeed shows a promising way to investigate the Fano resonances in photoionization of atoms within the MCDF scheme, although there are some discrepancies in the present calculations of the 2s2p ³P₁ state.