Measuring configurational entropy of glasses using population annealing

In this talk we present two methods to calculate the vibrational (S_vib) and configurational (S_c) entropies of glassy fluids in the context of population annealing Monte Carlo. The first method for obtaining S_vib integrates the pressure of individual configurations from the fluid phase to the glass phase, and the second method introduces a hard shell constraining potential to individual particles at fixed packing fraction in the glassy regime and integrates the entropy to the highly constrained, ideal gas limit. From population annealing, we also obtain the total entropy, S_tot, and from it the configurational entropy, S_c = S_tot – S_vib. We present numerical data for large-scale population annealing simulations of binary hard sphere fluids with 30, 60, and 100 particles. Our results show that the two methods agree and that for even modest-sized systems, finite-size effects appear to be small.