Time-dependent close-coupling method for electron-impact ionization of atoms

The electron-impact ionization of atoms is studied by direct solution of a set of time-dependent close-coupled partial differential equations. The close-coupled equations describe the propagation of a time evolving wavepacket on a two-dimensional radial lattice. Total excitation and ionization cross sections are obtained by projecting the wavepacket onto stationary states of the target following the collision. The electron-impact ionization cross section for hydrogen is compared with previous theoretical results and experiment. Preliminary results will be presented for positron scattering from hydrogen and electron scattering from hydrogen in a laser field