DOUBLY-EXCITED STATES OF POSITIVE-IONS - DEPENDENCES OF ENERGIES AND WAVE-FUNCTIONS ON NUCLEAR CHARGE-Z

Doubly excited intrashell states near the lower edge of n2 manifolds a re studied. The interelectronic repulsion is estimated within the two- electron dipole approximation. When diagonalizing the two-electron Ham iltonian operator one obtains an analytical dependence of wavefunction s on quantum numbers and the nuclear charge Z. The three first terms o f the Z-1 expansion of energies are found as explicit functions of qua ntum numbers. The comparison with accurate data demonstrates the appli cability of the expressions obtained for reliable estimates of the pro perties of helium-like positive ions and the neutral atom He.