Does the time-dependent close-coupling approximation predict symmetric single differential cross sections for electron ionization of hydrogen?

The single differential cross section (SDCS) for electron-impact single ion ization should be symmetrical about half the total energy of the system. Ho wever, numerical results for the convergent close-coupling approximation do not exhibit this symmetry. Consequently, a controversy has arisen as to wh ether this is characteristic for all fully converged time-independent close -coupling calculations or whether this indicates a lack of convergence. In this paper, the behaviour of the SDCS is examined for time-dependent close- coupling calculations and it is found that a fully converged calculation wo uld be symmetrical about half the total energy.