The formulae for electrostatic interaction between the configurations nl(N2,) nl(N+1)n'l', nl(N)n'l'n " l ", nl(N)n'l'(2), nl(N-l)n'l'n " s(2) and th
e configuration nl(N-l)n'l'(2)n " l " are given.
The formulae will be applied to the fine structure analysis of even configu
rations of the europium atom Eu I.