Optical potential approach for scattering of electrons by ions

Currently, limited basis set close-coupling calculations represent the ''state of the art'' for the scattering of electrons by atoms and ions in the intermediate energy range. An addition of a matrix optical potential to a close-coupling scheme is described here and it is suggested that it should lead to improved results, particularly for scattering from excited states. The optical potential is evaluated with the use of a pseudostate basis of expansion. The resulting set of coupled integrodifferential equations are solved by an integral equation linear-algebraic method. Results for the excitation of singly-charged helium ion from ground state to the 2s and 2p states by electron impact are presented