Dl. Shepelyansky, ANALYTICAL DETERMINATION OF STABLE CONFIGURATIONS IN DOUBLY-EXCITED ATOMS AND IONS, Journal of physics. B, Atomic molecular and optical physics, 27(11), 1994, pp. 120000235-120000242
A simple approach is proposed to determine analytically the classicall
y stable configurations of doubly excited states in atoms and Z ions,
in the case when both electrons are, located on one side of the nucleu
s. An analytical formula gives the ratio between the electron distance
s within the 1% accuracy of the existing numerical computations.