2pnp (1,3Pe) states of neutral He and Li+ ions under Debye plasma screening

The energy eigenvalues of doubly excited 2pnp (1Pe) (n = 3-8) and 2pnp (3Pe) (n = 2-7) bound states of a neutral helium atom and singly ionized lithium atom are estimated under weakly coupled plasma screening for the first time using an explicitly correlated Hylleraas-type basis in the framework of the Rayleigh-Ritz variational principle. The Debye screening model has been employed to include the effect of plasma background. Improvement over the existing approximated theoretical results has been achieved for the above-mentioned states of neutral helium under Debye plasma screening. The modified energy eigenvalues of 1,3Pe states arising from two p electrons of a Li+ ion in the Debye plasma environment are being reported for the first time.