Aging and protocol dependence of thermal activation events in structural glasses

In this study, we investigate the waiting time dependence and the protocol dependence of thermally activated events in structural glasses using molecular simulations and potential energy landscape analysis. We find a qualitative crossover in the nature of activation events; from avalanche-like events to local events. We also use the isoconfigurational ensemble analysis and reveal that the events become less diverse and more reversible. We discuss these crossovers from the perspective of the stability and the potential energy landscape of glasses. To investigate the protocol dependence, we compare the two types of glasses whose stability is controlled by waiting time and parent temperature, respectively. Surprisingly, at the same inherent structure energy level, the parent-temperature-controlled glasses are more unstable and maintain their avalanche-like nature. These results demonstrate that the activation properties of structural glasses are not determined solely by their energy levels, highlighting the essential role of state connectivity and the dynamical sampling in the complex energy landscape.