National Institute of Standards and Technology

Below is an animation of 13 Lennard-Jones particles moving in an equilibrium, supercooled liquid consisting of 8000 total LJ particles (not shown). These particles are among the most mobile in the system on the timescale of this animation, which is substantially less than the primary (alpha) relaxation. [Note: There are 40 frames in the movie; the time between each frame is substantially longer than the elementary time step of the simulation (so the motion does not appear smooth.)] We see that during the movie, each particle moves approximately one interparticle distance, essentially replacing a neighboring particle in the string. Although this particular string closes on itself into a ring, most strings observed in the simulation do not.