FIGURE 6 is near here
Figure 6 presents the regions of electronic concentration and depletion along each bond in the six dimers; both the contour maps (left) and relief maps (right) of ∇2ρ (b) are shown. The blue points denote BCPs. The blue lines denote positive Laplacian of electron density, which indicate interactions of an ionic character (e.g. van der Waals or intermolecular interactions), and the red lines denote negative Laplacian of electron density which indicate covalent bonds. The corresponding values of the Laplacian of electron density are listed in Table 6. Relief maps provide an intuitive view of the Laplacian of electron density, the curves above the plane show the positive Laplacian of electron density, and the curves below the plane show the negative Laplacian of electron density.