# S-states of helium-like ions

## Description

Abstract A simple Mathematica (version 7) code for computing S-state energies and wave functions of two-electron (helium-like) ions is presented. The elegant technique derived from the classical papers of Pekeris (1958, 1959, 1962, 1965, 1971) [1-3] is applied. The basis functions are composed of the Laguerre functions. The method is based on the perimetric coordinates and specific properties of the Laguerre polynomials. Direct solution of the generalized eigenvalues and eigenvectors problem is used, ... Title of program: TwoElAtomSL(SH) Catalogue Id: AEHY_v1_0 Nature of problem The Schrödinger equation for atoms (ions) with more than one electron has not been solved analytically. Approximate methods must be applied in order to obtain the wave functions or another physical attributes from quantum mechanical calculations. Versions of this program held in the CPC repository in Mendeley Data AEHY_v1_0; TwoElAtomSL(SH); 10.1016/j.cpc.2010.11.031 AEHY_v2_0; TwoElAtomSL(SH); 10.1016/j.cpc.2011.11.001 This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018)