| Abstract Scope |
Many glassy materials’ properties originate from collective rearrangements of atoms called local structural excitations(LSEs). In a classical picture, shear loading reduces LSE’s activation energy, in analogy to the dislocation migration picture in crystals where the Peierls valley in potential energy landscape(PEL) is biased and tilted by external shear. However, the direct track of minimum energy pathways in PEL before and after shear loading by atomistic modeling shows only slight tilting, yielding an unreasonably small activation volume (10 times less than experiments). Here, we show that under external shear the system’s PEL topology is qualitatively changed. It becomes more fractal, where tortuous pathways with large ratio of contour length and end-to-end length start to emerge. Those tortuous pathways have significantly lower activation barriers, which can naturally explain the enhanced LSEs’ activities estimated in experiments. The potential energy confinement zones for individual atoms and their correlations with energy dissipations are also discussed. |