Wave Functions for the Ground State of Lithium and Three-Electron Ions

Improved wave functions and ionization potentials have been obtained for the configuration 1s2 2s, by using the variation method with a variation function containing four parameters. The wave function for the whole atom is of the determinant form, built up of K and L single-electron functions. The K function used is hydrogen-like with one parameter, the effective nuclear charge, and the L function is of the form αre—ηr—e—ζr. A simple rule is obtained by means of which it is possible to write down the wave function for any three-electron ion without further calculation. The deviation of the calculated ionization potentials from the observed values is 0.9 percent for Li I and decreases to 0.3 percent for C IV. Comparison is made with the results of other investigators and curves showing the wave functions and electron density functions are given.