Density and geometry of excitations in supercooled liquids up to the activation energy

We introduce an algorithm to uncover the activated particle rearrangements, or excitations, regulating structural relaxation in glasses at much higher energies than previously achieved. We use it to investigate the density and geometric properties of excitations in a model system. We find that the density of excitations behaves as a shifted power-law, and confirm that this shift accounts for the increase in the activation energy controlling the relaxation dynamics. Remarkably, we find that excitations comprise a core whose properties, including the displacement of the particle moving the most, scale as a power-law of their activation energy and do not depend on temperature. Excitations also present an outer deformation field that depends on the material stability and, hence, on temperature. Our analysis suggests that while excitations suppress the transition of dynamical arrest predicted by mean-field theories, they are strongly influenced by it.