Spatial segregation in mixtures of soft diskswith velocity constrains

ALEJANDRO SEIF; GRIGERA T. S.; BAGLIETTO, GABRIEL; WOLFGANG PAUL

Workshop; Statistical Mechanics of Swarming Behaviour; 2019

We study the behaviour of mixtures of self-propelled soft disks (Lennard-Jones-likerepulsion) with the constrain that the speeds of the particles remain constant duringcollisions. Particles are identical except by their speeds values. We studied mixturesof slow and fast particles. At high densities, a by-speed segregation is observed whenthe particle speeds are different enough. Using the structural correlation functionsg(r) and the structure factor S(k), we were able to determine the existence of anhexatic-like phase in the slow particles set for very small values of their speeds.This means that in addition to the segregation observed, the slow particles beginto develop quasi-long range correlations as their speeds decrease. We propose amesoscopic theory that qualitatively explains the phases in the system by means ofa minimisation principle involving the number of collisions in the steady state.