Quasivoids in Polydisperse Glassy Systems With Atomistic PEL Exploration and Iso‐Configuration Method

ABSTRACT Understanding the microscopic relaxation mechanisms in amorphous solids remains a fundamental challenge. A theoretical framework posits that dynamics are mediated by quasivoids: transient, localized quasi‐particles that are the amorphous analogue of crystalline vacancies. Unlike a simple void, a quasivoid consists of fragmented, distributed free volume that is collectively reassembled to accommodate an atomic hop. In this work, we investigate these elementary relaxation events by exploring the potential energy landscape (PEL) of a model polydisperse glass using the activation–relaxation technique nouveau (ARTn), an open‐ended algorithm designed to efficiently locate transition saddle points on the PEL. By analyzing 4910 independent activated events, we find that structural relaxations are highly localized, typically involving a small number of atoms (1–6), and are characterized by energy barriers uncorrelated with the net energy change of the event. Visualization of the atomic trajectories reveals that these events manifest as string‐like cooperative motions. Crucially, we provide a direct, atom‐resolved visualization of a relaxation cascade where the presence of a quasivoid facilitates an initial atomic hop, which in turn effectively transports the quasivoid, enabling subsequent hops along the chain. These results offer computational evidence for the role of quasivoids as fundamental defect‐like excitations that trigger string‐like structural relaxations, providing a physical basis for dynamics in amorphous materials.