Figure 3.

Illustration of the RDF. (A) A 2D system of N = 20 particles in a circle of radius R = 4. The particles arrange around the reference particle at the origin (red circle) in a certain manner. To determine the RDF, the circle is subdivided into spherical shells of thickness Δr = 1. (B) In the next step, the number of particles in each spherical shell is counted (blue bars). This is contrasted to the expected average number of particles if all 20 particles were randomly distributed inside the area (gray bars). (C) The RDF is now obtained by taking the ratio between actual density and average density. The model system shown here displays a particle depletion for short distances (r < 1), indicating a repulsive short-range potential.