Structural properties of Li atom under quantum and classical plasmas: A composite variational framework

Abstract

Structural properties of 1s 2 nl ( 2 L) [n = 2-5, l = 0-4; where, n and l are the principal quantum number and orbital angular momentum quantum number, respectively] states of Li atom embedded in classical weakly coupled plasma (WCP) and dense quantum plasma (DQP) have been discussed.The Debye-Hückel potential or the screened-Coulomb potential (SCP) and exponential-cosine-screened Coulomb potential (ECSCP) have been used to mimic the WCP and DQP, respectively. Li atom has been treated as a composite system with a frozen core Li + ion and a chemically active valence electron. The Rayleigh-Ritz variational method with Hylleraas-type basis set has been used to estimate the energy eigenvalue of 1s 2 ( 1 S) state of Li + ion core and a pure exponential basis has been considered to compute the energy of nl ( 2 L) states of the valence electron of Li atom. The influence of ECSCP and SCP on the radial probability distribution of the valence electron of the Li atom has also been studied. K E Y W O R D Sclasscial plasma, lithium atom, quantum plasma, ritz variational method, structural properties INTRODUCTIONThe studies on atomic processes in plasmas are gaining momentum over the years with the gradual development of the experimental facilities to have controlled laboratory plasma with homogeneous temperature and density. The availability of the astrophysical data from stellar and interstellar surroundings e.g. stars, interstellar gas, solar corona, solar wind, gaseous nebulae, cometary tails, rings of Saturn etc. adds as another reason for such investigations. Extensive review articles on the progress of such investigations are now available in the literature. [1,2] Based on the different plasma parameters, plasmas are classified into numerous types. The screened Coulomb potential or Debye-Hückel potential [3] defined asis used to mimic classical weakly coupled plasma (WCP). The plasma screening parameter depends on the plasma particle charge (q), plasma density (n e ), and plasma temperature (T) as follows-= √4 n e q 2 K B T , where K B is the Boltzmann constant. In case of WCP, the plasma temperature (T) is very high whereas the plasma density (n e ) is very low. The