bool OECalculateSurfacePotentials(OESurface& surface,
                                        const OEChem::OEMolBase& target,
                                        const bool grasp = false);

Will calculate atomic potentials and assign those potentials to surface vertices on the supplied surface. The optional parameter grasp set to true will calculate the potentials based on the GRASP method, which is a coarser perspective of the potential using formal charges.