As shown in Figure , the electric field affects the adsorption energies of standing and lying categories very differently. We find that negative fields (F < 0 V nm -1 ) destabilize the adsorbed molecules, while positive fields stabilize the adsorption. However, the effect is quite strong for standing molecules, for which the adsorption energy changes by more than 1 eV between -3 V nm -1 and +3 V nm -1 . Conversely, lying molecules are less affected, with E ads differing only by ca. 0.14 eV within the field strengths considered. As mentioned above, this is due to the interplay of E geom and E bond . The two components respond differently to the electric field for different adsorption geometries. For the lying category, both components of the adsorption energy, E geom and E bond , change by several 100 meV with the field. However, as these two contributions occur in similar magnitude, but with a different sign, these changes cancel each other for the adsorption energy. Conversely, for standing E geom is almost constant, while E bond changes even more than for lying.