Rotations of molecules driven by current are possible basis for construction of molecular motors. In "Geländer" molecules, the chiral structure was thought to drive the momentum transfer from travelling electrons to the molecule.
We construct a simple model, motivated by our DFT based study, to explore the structure of the current density in such a molecule and identify the regions of the molecule that contribute majority of the angular momentum of the electron current. We also discuss the particularities of our results, especially the conservation of rotation direction under the exchange of electric bias direction.
The results are compared with experimental observations.