[en] We propose a model for studying quantum mechanical corrections to the window formula derived by Swiatecki on a classical basis. The model consists in describing the colliding nuclei by two equal cubic boxes each having an opening initially closed by the wall of the other box. When the boxes start to slide a window is created which opens and closes. We calculate the transfer of nucleons and the momentum flux from one nucleus to the other. These quantities are obtained by solving the time dependent Schroedinger equation with initial conditions representing one box full and the other empty (one sided flux). The flux of nucleons gives a measure of the energy and relative momentum transferred from the relative to the internal motion