Dynamics of topological defects and the effects of the cooling rate on finite-size two-dimensional screened Coulomb clusters

The formation of dislocations, disclinations and their dynamics is central to our understanding of crystalline materials. Here, the dynamics of these topological defects in two-dimensional (2D) clusters of charged classical particles interacting through a screened Coulomb potential is investigated through the molecular-dynamics (MD) simulation technique. The particles are confined by a harmonic potential and coupled to an Anderson heat reservoir. We investigate cooling rate effects on the defect dynamics by decreasing the temperature of the heat reservoir linear in time. We found that: i) the mobility of the defects strongly depends on the number of nearest neighbors and the nature of those defects, ii) geometrically induced defects have different dynamics than other defects because of spontaneous pinning of the defects at the corners of the hexagon, and iii) if the cooling speed is large enough, the system ends up in a non-equilibrium state and a glass-like structure is formed