The Van der Waals potential is commonly described as a "6-12" potential
The VDW hard sphere radii can be used to define a volume of each atom.
A sphere of the VDW radius is drawn around each atom center.
Overlaps are truncated by planes equidistant from the atom centers.
(Or the truncating plane may be positioned at a distance proportional to the ratio of the VDW radii of the two atoms.)