2-ELECTRON ATOMS - O(4,2) OPERATOR REPLACEMENTS AND LARGE-ORDER PERTURBATION-THEORY WITH RESPECT TO THE REPLACED KINETIC-ENERGY OPERATOR

The Schrodinger equation-for two-electron atoms is transformed into an alternative equation depending on a free dimensionless parameter beta , according to the method of o(4,2) operator replacements. These opera tor replacements are well defined except for the case where both the o rbital and spin momenta are zero, i.e., except for Singlet S states. W hen P goes to positive infinity, the solutions of this present equatio n should correspond to the solutions of the Schrodinger equation. When B goes to negative infinity, the present equation becomes exactly sol vable. These exact solutions are the zero-order solutions for a Raylei gh-Schrodinger perturbative expansion where the perturbation is the no ndiagonal part of the replaced kinetic-energy operator. An essential p roperty of this method is that the perturbative operator is bounded, a nd therefore the convergence radius of the series is nonzero. The meth od is purely nonvariational. A numerical application for the triplet S even-parity ground-state helium atom is performed.