An explicitly correlated helium wave function in hyperspherical coordinates

Coordinate system: R,t,r12. Simplified solution - spinless part: Ψ=∑i,j,kCi,j,kRir12jtrke-ζR. Necessary condition for simplified wave function (which should be a formal solution of 3Body Schrödinger equation): inclusion of the terms r12j/Rj′-2 where j′=0,…,j-2 for j⩾2. 36