A custom external force that we call a "continuity force" is added, which ensures that the particles form an unbroken network of interactions. More precisely, if we imagine the particles as nodes of a network and draw an edge between particles that are closer than a cutoff distance (d), then the nodes would all be in the same component of the network. In other words, there exists a path of some length between any two nodes i and j. The continuity force achieves this by classifying particles into components on the fly and adding an attractive force between pairs of particles belonging to different components. The particles are chosen each dynamics step as the closest possible pairs between the two components. The attractive force is of the form , where r is the separation between the particles and d is a user-defined cutoff distance.