Microscopic Picture of Aging in SiO2: A Computer Simulation
Katharina Vollmayr-Lee (Department of Physics & Astronomy, Bucknell University)

Using molecular dynamics computer simulations, we study the aging dynamics of amorphous SiO2. Starting from fully equilibrated configurations at high temperatures the system is quenched to temperatures which are below Tc. We then observe the resulting microscopic dynamics as a function of the waiting time tw, the time elapsed since the temperature quench. We use single particle trajectories to identify "jumps" when the particle's average position changes over a short time interval significantly compared to its fluctuations. We find that the only tw-dependent microscopic quantity is the number of jumping particles per unit time. Similar to previous studies for fragile glass formers, we show here for the strong glass former SiO2 that neither the distribution of jump lengths nor the distribution of times spent in the cage are tw-dependent. We therefore find a surprising similarity of the jump dynamics of fragile and strong glass formers.