Analytic Approximations for Integrated Electron?Atom Excitations

Abstract

Accurate calculations of atomic excitations require estimates of the effect of higher excitations on the effective (optical) potential coupling various reaction channels. The total cross section for a particular excitation is proportional to the maximum contribution of that excitation to the imaginary part of the elastic momentum-space optical potential, and is typical of the contribution to the potential in general. Analytic expressions relevant to the calculation of optical potentials are given Their validity is estimated by comparison with more-accurate calculations and with experimental excitation cross sections.