Removal of Electron—Electron Poles from Many-Electron Hamiltonians

In many-electron problems, the Hamiltonian has poles 1/rij which produce difficulties in the solution of the Schrödinger equation HΨ = EΨ. If Ψ is taken to be φχ where φ= ∏ i>j[1+12rijexp(−αrij)],it is found that χ satisfies the new Schrödinger equation H′χ=Eχ where the new Hamiltonian H′ has no electron—electron poles.