Fig. 2: Diffusivity and time to reach the steady state.
From: Yielding behaviour of active particles in bulk and in confinement
a, MSD for different magnitudes of the active force showing a transition from an absorbing (non-diffusive) to a diffusive state for the well-annealed case. The black dashed lines are linear best fits to the data. b, Change in diffusivity with the active force magnitude, for both poorly annealed and well-annealed samples, shown for values of the active force for which the MSD shows a diffusive regime within the minimum expected waiting time for particles to escape the cage of their local neighbourhood (Supplementary Information). The diffusivity data for f > 0.8 are fit to a power law (dashed magenta vertical line indicates the lowest f for which the diffusivity data are included in the fitting procedure), with data for f < 0.8 in reasonable agreement with the extrapolation from the fit. The dashed blue vertical line marks the value of f at which tss goes through a maximum in d for the poorly annealed case. The extrapolation of the diffusivity data indicates a vanishing diffusivity at f = 0.43. c, Relaxation curves for energy versus active force, obtained by averaging over eight independent trajectories in logarithmically spaced time intervals. d, Relaxation times tss exhibiting divergence at the yielding transition. The dashed black and red lines are the best fits to the data. e, Relaxation curves for potential energy versus number of cycles for stress-controlled cyclic shear simulations, obtained by averaging over 16 independent trajectories in logarithmically spaced time intervals. f, Relaxation times, measured from the fluidization time for well-annealed samples, exhibiting divergence at the yielding transition (the dashed red line is the best fit to the data) with σyield = 0.735 and exponent β = 1.87 (Supplementary Information provides further discussion on exponents).
