In the previous discussion, we ignored the contribution to the current density from polarization functions. We show in Figure that a small part of the current density through the π-system is explained by polarization functions that can form π-bonds. In our calculations, the polarization functions consist of d-functions which means that, by symmetry, only dxz can form π-bonds: with itself (dxz -dxz) or with pz (pz -dxz). Both of these bonds also have a node in the plane of the molecule thus the conclusion is the same. See Figure for a plot of a dxz-orbital.