Aging of a hard-sphere glass: effect of the microscopic dynamics

We present simulations of the aging of a quasi-hard-sphere glass, with Newtonian and Brownian microscopic dynamics. The system is equilibrated at the desired density (above the glass transition in hard spheres) with short-range attractions, which are removed at t = 0. The structural part of the decay of the density correlation function can be time rescaled to collapse onto a master function independent of the waiting time, t(w), and the timescale follows a power law with t(w), with exponent z ∼ 0.89; the non-ergodicity parameter is larger than that of the glass transition point (the localization length is smaller) and oscillates in harmony with S(q). The aging with both microscopic dynamics is identical, except for a scale factor from the age in Newtonian to the age in Brownian dynamics. This factor is approximately the same as that which scales the α-decay of the correlation function in fluids close to the glass transition.