Ground-state correlation effects in He-He inelastic scattering

Abstract
Excitations of one or both atoms to either a 21P or 31P state are considered along with the example of a mixed (21P, 31P) transition. Correlation effects were found to be most important when both atoms were excited, the cross sections being reduced by about a quarter at low impact energies. For the description of angular correlation within He (11S), configurations based on p orbitals were always the most significant thus reflecting the symmetry of the excited states. A brief comment is made regarding the elastic cross sections at large impact energies.