Configurational entropy Configurational Entropy of Self Propelled Glass Formers

The configurational entropy is an indispensable tool to describe super-cooled
liquids near the glass transition. Its calculation requires the enumeration of
basins in the potential energy landscape and when available, it reveals a direct
connection with the relaxation time of the liquid. While there are several reports
on the measurement of configurational entropy in passive liquids, very little is
understood about its role in active liquids which have a propensity to undergo a
glass transition at low temperatures. In this paper, we report a careful calcula-
tion of the configurational entropy in a model glass former where the constituent
units are self propelled. We show that unlike passive liquids, the anharmonic
contribution to the glass entropy in these self-propelled liquids can be of the
same order as the harmonic contribution, and therefore must be included in cal-
culation of the configurational entropy. Our extracted configurational entropy
is in good agreement with the generalized Adam-Gibbs relation predicted by
the random first order transition theory enabling us to deduce a scaling relation
between configurational entropy and a point-to-set length scale in these active
systems. Our findings could be of great utility in conventional active systems
such as self-propelled granules, Janus particles and dense bacterial suspensions,
to mention a few.