Sensitivity of Differential Cross Sections and Angular Correlation Parameters to Scattering Parameters

Discusses methods for calculating distorted-wave amplitudes. It is difficult to compare the relative merits of these calculations since widely different atomic potentials and wavefunctions have been used in the various calculations. The authors have examined these different approximations by calculating different distorted-wave amplitudes using a common Hartree-Fock basis for atomic potentials and wavefunctions. This procedure allows one to examine the relative effects of different types of approximations. For purposes of comparison, they have calculated differential cross sections and angular correlation parameters for electron impact excitation of the 21P and 31P allowed transitions of helium for incident electron energies in the range 40-200 eV. All of the calculations include both the direct and exchange amplitudes, and calculations were performed using both a static atomic distorting potential and a complex optical potential which included polarisation, exchange and absorption distortion in addition to the distortion of the static potential