Configurational entropy Configurational Entropy of Self Propelled Glass Formers
Description
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.
Files
Steps to reproduce
We have developed our own code that was originally written by Ashwin Joy. New features and modules were later added by Sachin C N and Dipanwita Ghoshal to perform numerical simulations of the athermal active binary liquid. We first benchmarked our code to produce figures/results from the well known reference of E. Flenner, G. Szamel, L. Berthier, Soft matter 12 (2016) 7136-7149. The code has also been used to report findings on the connection between growing time scales and length scales in active glass forming liquids, D. Ghoshal and Ashwin Joy, Physical Review E 102, 062605 (2020) and to provide an entropic scaling relations in active glass forming systems, Sachin C N and Ashwin Joy, Physica A, Volume 588, 15 February 2022, 126578. To extract the harmonic contribution to the glass entropy, we used an open source #C program code of the conjugate gradient method and modified it according to our system to obtain energy minimized states (Inherent structures). To evaluate the Hessian matrix, we developed a #C program code and using the LAPACK package (version 3.11.0) of C library we calculated the normal modes of vibrations.