Theoretical Study On The Energy Level Structure Of Bound States Of Helium-like Ions In A Quantum Plasma Environmen

In recent years,due to the rapid development of plasma in the atomic and molecular fields,the study of the structural properties of the helium-like system inside the plasma has become a hot topic.The interaction between charged particles in a dense quantum plasma is simulated with the exponential cosine screened Coulomb potential within the framework of the Rayleigh-Ritz variational principle,using the Slater-type orbital configuration-interaction(STO-CI)basis functions and the explicitly correlated Hylleraas configuration-interaction(HyCI)basis functions,and the bound state energies of two-electron atoms(Z=6,7,8,9,10,12,14,16,18,20,25,30,35,40,45,50)for the ground state and bound state energies for the single excited state(1 snl 1,3L n≤3),giving the ionisation energies of the studied atomic systems and analysing the correctness of the Hund rule for high-Z atoms in dense quantum plasmas.In addition,the expected values of the radial and angular geometries of the ground states of ions and He atoms in dense quantum plasmas(r),(r-1),(r2),(r12),<r12-1),<r122),(cosθ1),(cosθ12)and<θ12>are calculated using the HyCI basis functions.An in-depth test and detailed comparison of the high-precision computational capabilities of two wave functions dealing with screened twoelectron atoms is presented.Energies varying with Z and screening parameters are obtained with high computational accuracy,and they have been shown to be convergent by systematically increasing the terms in the wave functions.For certain two-electron atoms with high Z values,a formula for the energy of bound states in quantum plasmas is given for the first time in this work.The present calculations for free atoms show good agreement with other state-ofthe-art predictions,and we improve on previous calculations in the dense quantum plasma environment,especially in the case of large screening parameters.Radial expectation values,and inter-electron angles,for plasma screening ions and He atoms are reported for the first time,and we show that the combination of them provides a fairly good description of the geometric structure of two-electron atoms in different screening conditions.We finally analyze the asymptotic behavior of ground state energies and radial quantities for two-electron systems nearing the bound-continuum limit and provide strong evidences that the two-electron critical screening parameters are in coincidence with those for one-electron atoms.