Eikonal optical-model theory of elastic electron--atom scattering

We analyze elastic electron-atom scattering at intermediate and high energies by using a second-order optical-model potential together with the eikonal approximation. We devote particular attention to the role of long-range forces and formulate the theory in a way suitable for generalizations to complex target atoms. We also study the relationship between the optical eikonal model and the Born series, and include exchange effects to leading order in the inverse power of the energy. Our optical-model theory is then illustrated by a detailed analysis of elastic electron-helium scattering for incident-electron energies ranging from 100 to 500 eV. We find excellent agreement with experimental data without using any phenomenological parameter.