Convergent Close-Coupling Approach to Electron—Atom Collisions

Abstract

The convergent close-coupling (CCC) method was developed in order to resolve the long-standing discrepancy between two consistent experiments and all available theories for 2p excitation of atomic hydrogen [1] . The method was unable to resolve this discrepancy, but subsequent experiments [2,3] found much more in favor of theory than the previous experiments. There have been a number of reviews of the applications of the CCC theory with the most recent one being by Bray et al. [4] . The method has been extended to ionization [5], resulting in some controversy [6,7] that required further explanation [8,9]. Our own confidence in the ability of the CCC method to reproduce electron— hydrogen fully differential ionization cross sections was shaken by the less than satisfactory agreement with experiment [10] . However, this turned out to be primarily due to insufficient computational resources available at the time [11]. Consequently, we are now confident that the CCC method is able to solve the e—H, γ—He, and e—He (within the frozen-core model) collision systems at all energies with one or two outgoing electrons. We shall attempt to explain here the underlying foundations as clearly as possible. The example of the S-wave model will be used to demonstrate the method. A published program is available that shows the workings of the method discussed here [12] . We will finish by concentrating on the application of the method to fully differential ionization processes.KeywordsFinite Difference MethodTotal Wave FunctionOutgoing ElectronTotal Ionization Cross SectionIonization AmplitudeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.