Bound S-states of a two-electron atom

A special selection of the Euler angles is made, according to which one axis of the rotating coordinate system is related to the center of mass of electrons. The hierarchy of the hyperspherical coordinates R, alpha, and theta allows sequential quantization with respect to these variables to be performed. The complex structure of the potential with respect to the R coordinate leads to the use of a quasi-classical approximation. The energy spectrum of doubly excited S-states of a He atom is determined. The results are compared to other published data. (C) 2002 MAIK "Nauka/Interperiodica".