  We have implemented the paraxial approximation followed by the time-dependent
Hartree-Fock method with frozen core for the single impact ionization of atoms
and two-atomic molecules. It reduces the original scattering problem to the
five-dimensional time-dependent Schr\"odinger equation solution. By using this
method we calculated the multi-fold differential cross section of the impact
single ionization of the helium atom, the hydrogen molecule and the nitrogen
molecule by the intermediate energy electrons. Our results for the helium and
the hydrogen are quite close to experimental data, but for N$_2$ the agreement
is worse apparently because of the insufficiency of the frozen core
approximation.
