van der Waals interactions are described by the Lennard-Jones potential. This consists of a longer-range attractive component (resulting from induced-dipole:induced-dipole attraction) and a short-range repulsion (resulting from the repulsion of positively charged nuclei).
We will look at a simulator which shows the energy between two interacting atoms.
To start the simulator, from the PhET Interactive Simulations project at the University of Colorado Boulder, click here. Drag and release the image of the atom where indicated and watch the energy graph above as the atoms move with respect to one another. Try changing the parameters, e.g. atom types, and see what happens. Then try adjusting the atom diameter and interaction strength using the 'Custom Attraction' option. There is also an option to display the magnitude and direction of forces as arrows.