Movies and Animation for "Repetition and pair-interaction of string-like hopping motions in glassy polymers"

Chi-Hang Lam

Department of Applied Physics, Hong Kong Polytechnic University

(A) Coarse-grained trajectories of hopped particles

Glassy polymer is simulated using molecular dynamics (MD) simulation of a bead-spring model of polymer. Lennard-Jones (LJ) units are assumed in the simulation. The cubic box has a length 24.3 following periodic boundary conditions and contains 1500 chains each with 10 monomers. We now describe the videos in terms of video playtime, 1 second of which corresponds to a duration of 2500 and 5000 for the simulations at temperature T=0.36 and 0.32 respectively, At playtime t0, a video shows particle coarse-grained trajectories during [t0, t0 + 1s]. Only hopped particles, which displace more than 0.6 during any subinterval of the period, are shown. A segment in a trajectory is colored according to playtime t' at which the corresponding displacement occurs. Specifically, (t' mod 1s) serves as the index to the color bar below. Therefore, a simple string-like motion admits fixed coloring and will be displayed for 1s. Rapidly repeating string-like motions will be shown with time-varying colors and last for more than 1s. Slowly repeating ones will appear, disappear, and then appear again in general in different colors. (Color bar: )

T=0.36 ( hops036.mp4, 18 MB 5 fps 1280x960 5:47 )

T=0.32 (hops032.mp4, 19 MB 166s 10 fps 1280x960 3:19 )

(B) Repetitive particle hoppings in an incoherent string

The animation below shows the motions of particles in an incoherent string in a simulation at T=0.32. Each second of playtime corresponds to a duration of 1000 in the simulation. Only hopped particles in the local region, which displace more than 0.6 during the period, are shown. Particle positions are time-averaged in the same way as in the coarse-grained trajectories. Different polymer chains are colored differently. (str_incoherent.gif, animated GIF, 2 fps, 30 seconds)