Time-dependent close-coupling calculations of the triple-differential cross section for electron-impact ionization of hydrogen

The formulation of the time-dependent close-coupling method is extended to allow the calculation of electron-impact triple-differential cross sections for atoms. The fully quantal method is applied to the electronimpact ionization of hydrogen at an incident energy of 54.4 eV for various scattering geometries. The timedependent close-coupling results are found to be in very good agreement with those obtained by a timeindependent exterior complex-scaling method. On the other hand, even though the incident energy is relatively large, significant differences are found between the two nonperturbative cross-section results and those obtained using perturbative distorted-wave methods. Large differences are found for those geometries that require an accurate knowledge of the correlation between two outgoing continuum electrons in the presence of a Coulomb nuclear field.