Unphysical reflection phenomena involved in the numerical calculation of heavy-ion scattering cross-sections

The problem of the most suitable choice of the truncation point in the numerical solution of the Schroedinger equation for heavy-ion elastic-scattering phenomena is discussed. A relation between the exact scattering function and that obtained numerically has been derived. By using the WKB approximation the numerically calculated scattering function is simply expressed as the sum of the exact one and a term describing the reflection at the unphysical discontinuity due to the truncation of the integration procedure. A simple criterion is given for selecting the most appropriate truncation point. (author)