Correlated expansions ofn1Sandn3Sstates for two-electron atoms in exponential cosine scre

Abstract

Two-electron atoms embedded in a plasma environment are studied with screened and exponential cosine screened Coulomb model potentials. Within a configuration interaction approach, and using parameter-free explicitly correlated basis functions, we have calculated the ground-state and first excited-state energies (and other mean values) for H − , He, and Li + . We analyze their evolution with the screening parameter and provide simple fits, which allow for practical and rapid evaluations for example in plasma applications.

Calculation of screened Coulomb potential matrices and its application to He bound and resonant states

“…The variations of bound-state energies for He atom in screening environment have already been investigated by authors employing different types of basis, such as the threeparameter correlated wave function of Lam and Varshni [21], the Hylleraas basis of Dai et al [24] and Hashino et al [26], the 15-parameter correlated wave function based on Slater orbitals of Saha et al [25], the exponential correlated basis of Kar and Ho [29,30], the B-spline CI basis of Lin et al [32], and the parameter-free C3-like basis of Ancarani and Rodriguez [33]. The present calculations are performed by using the CI A comprehensive comparison between these predictions is illustrated in Fig.…”

“…The agreement is generally within the same accuracy as those shown in Table II at λ = 0. The investigation on the evolution of physical quantities of He ground state is motivated by the work of Ancarani and Rodriguez [33]. Their investigations are restricted to the radial quantities and in a relatively weak screening environment (λ 1.2).…”

“…Bound energies of the ground, singly excited, and some doubly excited metastable bound states for the two-electron atoms or exotic three-body systems have been calculated with very high accuracy. Most recently, Ancarani and Rodriguez [33] have investigated the evolution of radial expectation values for the ground state of H − , He, and Li + atoms with respect to the screening parameter by using a C3-like basis. Such investigations on physical quantities other than bound energy are of special interest in furthering our understandings about the system structure and dynamics in a screening environment.…”

Energies and transition wavelengths for two-electron atoms under Debye screening

“…In recent years, there has been an increasing interest in the study of atomic systems under the influence of screened Coulomb potentials ( [1][2][3][4][5][6][7][8][9][10], references therein). The screened Coulomb potential can be represented by different models.…”

Low-energy electron elastic scattering and impact ionization with hydrogenlike helium in Debye plasmas

“…Whitten et al have used the close-coupling and distorted-wave methods to study the plasma-screening effects on the electron-impact excitations of hydrogenlike ions with both the Debye-Hückel and ion sphere model potentials [6]. Note that the electronic structures of two-electron ions in dense quantum plasmas with exponential cosine screened potentials have also been studied [29][30][31].…”