Effect of pins on force distributions in frictionless jammed systems

Important properties related to systems capable of jamming - such as the jamming threshold and contact force distributions - have been well-studied for a broad range of experimental systems and theoretical models. By introducing lattices of fixed pins of negligible size into two dimensional bidisperse systems with purely repulsive harmonic interactions, we provide a tuning parameter to systematically modify these properties. We find that these pin lattices in square, triangular, and random configurations can significantly alter the force distribution of the system near the jamming transition. For instance, there is an increasing prevalence of very weak contacts with increasing pin lattice density, and we examine “bucklers”, particles with d+1 contacts, to understand this behavior. Additionally, the presence of pins shifts the tail of the force distribution from exponential decay to a distribution with “fat tails”. We also examine the bond angle distributions which accompany these trends.