Figure visualizes Δρ plane-averaged for an electric field of F = 3 V nm -1 for the most stable standing and lying adsorption geometry. (A corresponding plot for F = -3 V nm -1 is shown in the Supporting Information). As is to be expected, there is an accumulation of charge on the surface of the substrate due to the polarization of the slab. Furthermore, the electrons in the standing molecule are more spread out, due to the spatial extent of the standing geometry in the direction of the field (i.e., perpendicular to the surface). Standing molecules also exhibit a high polarizability in the direction of the field. As a result, it is energetically more favorable to shift electrons into the standing geometry, which can, therefore, benefit more from the field than the lying geometry.