Transformation of the helium atom Schrödinger equation into integral form Original Research Article

We define the Greenʹs function for two identical particles moving in a Coulomb field. We use this Greenʹs function as a basis for deriving an integral equation of the helium atom Schrödinger equation by treating the electron repulsion term as a perturbation. The two-particle Greenʹs function is further simplified by means of a contour integration. An additional transformation does not lead to further simplification of the result.