Fig. 4. DORI maps of representative dimers for each type of dominant interaction (DORI isovalue: 0.9). Isosurfaces are color-coded31 with sgn(λ2)ρ(r) in the range from attractive −0.02 a.u. (red) to repulsive 0.02 a.u. (blue). In particular, sgn(λ2)ρ(r) < 0 characterizes covalent bonds or strongly attractive NCIs (e.g. H-bonds); sgn(λ2)ρ(r) ∼ 0 indicates weak attractive interactions (van der Waals); sgn(λ2)ρ(r) > 0 repulsive NCIs (e.g. steric clashes).
