Angular Correlation in the Helium Atom

Schwartz has shown that if the wave function for the ground state of He is developed as a perturbation series in powers of 1/Z and if the first-order wave function is expanded in a series of Legendre polynomials in the angle θ between the position vectors of the electrons, the contribution of the Pₗ component to the second-order energy behaves as l^-4 for large l. This same behavior is noted for a model atomic system.