Correlated interelectronic angle densities of two-electron atoms in position and momentum spaces

Based on multi-configuration Hartree–Fock calculations, correlated interelectronic angle densities are systematically reported for the first 10 members of two-electron atoms in both position and momentum spaces. In position space, the electron correlation is found to modify the uniform Hartree–Fock density so that the density migrates from a small to a large angle, resulting in an average interelectronic angle greater than 90°. In momentum space, however, the opposite is true and the two electrons prefer parallel momenta to inverse momenta.