  A review of some recently developed methods of calculating multiple
differential cross-sections of photoionization and electron impactionization of
atoms and molecules having two active electrons is presented. The methods imply
original approaches to calculating three-particle Coulomb wave functions. The
external complex scaling method and the formalism of the Schroedinger equation
with a source in the right-hand side are considered. Efficiency of the
time-dependent approaches to the scattering problem, such as the paraxial
approximation and the time-dependent scaling, is demonstrated. An original
numerical method elaborated by the authors for solving the 6D Schroedinger
equation for an atom with two active electrons, based on the Chang-Fano
transformation and the discrete variable representation, is formulated. Basing
on numerical simulations, the threshold behavior of angular distributions of
two-electron photoionization of the negative hydrogen ion and helium atom, and
multiple differential cross-sections of electron impact ionization of hydrogen
and nitrogen molecules are analyzed. It is demonstrated that the Wannier law
for the angular distribution of double ionisation is not correct even at very
small energies.
