Sensitivity of differential cross sections and angular correlation parameters to scattering parameters

Abstract

Over the last few years there have been several methods proposed by different investigators for calculating distorted-wave amplitudes. It is difficult to compare the relative merits of these calculations since widely different atomic potentials and wavefunc- tions have been used in the various calculations. We 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 us to examine the relative effects of different types of approximations. For purposes of comparison, we have calculated differential cross sections and angular correlation parameters for electron impact excitation of the 2'P and 3lP 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.