One might envision two small toy cars traveling down a set length of track. The centers of square well molecules, unlike the hard spheres, have the ability to come closer than 2R in distance. Because, at collision, the molecules deform, and their centers are able to come closer. Instead, they form clusters that are not broken until disturbed by an outside force. Interaction Perhaps, the most interesting event surrounding molecules is their inevitable interaction with each other.
Chemical reactions depend upon such collisions.
For 2 hard spheres to interact, their centers must be 2R apart. For purposes of simplicity, my simulations left the respective diameters of molecules A and B equal. A and B occurring is equal to 1 if the intermolecular distance 2R is equal to d. The probability of a reaction equals 0 otherwise, as the molecules will not interact unless their centers are 2R apart. In creating the applet, I needed to discover a way in which I could compute the interaction of the colliding particles.