The Lithium Atom and Three-electron Ions

The Lithium Atom and Three-electron Ions.—Table 31-1 lists the variation functions which have been tried for the lowest state of lithium, which has the configuration ls22s. All these functions are of the determinant type given in Equation 30-7 and in all of them the orbital part of uu(i) is of the form 

Experimental total energy —14.9674 experimental ionization potential  

2s function Total energy Differ- ence Ionization potential Differ- ence 

The next step to be taken is to apply a variation function to lithium which recognizes explicitly the instantaneous, instead of just the average, influence of the electrons on each other. Such functions were found necessary to secure really accurate results for helium (Sec. 29c), but their application to lithium 

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