Figure 2: Two situations in which the Gaussian functions would have contradictory properties. (a) Two atoms of the molecule, and , are just close enough to block the way to a solvent molecule . The point is on the SES and must be influenced by the filed generated by , . (b) and are close. The point is on the SES but also on the VdWS. So, it should not be influenced by . It is possible to show that in some (frequent) configurations, .