Atomic mechanism of glass-to-liquid transition in simple monatomic glasses

The atomic mechanism of a glass-to-liquid transition in a monatomic Lennard-Jones (LJ) glass was studied using the molecular dynamics (MD) method. Glassy models were heated up from low temperature at two different heating rates and a glass-to-liquid transition found to occur at the higher heating rate. The temperature dependence of the potential energy, mean-squared-displacements (MSD) of the atoms and the self-intermediate scattering function indicate clearly that a glass transition occurs in the system. The atomic mechanism of the glass-to-liquid transition was investigated by analyzing the spatio-temporal arrangement of liquid-like atoms in the system upon heating. Liquid-like atoms were detected using the Lindemann-melting-like criterion. Upon heating, liquid-like atoms occur at temperatures far below the glass transition temperature (T-g) due to local instabilities. Their number increases upon further heating and they form clusters. Subsequently, a single percolation cluster of liquid-like atoms appears, which spans the system at T-g. The percentage of liquid-like atoms aggregated into this single percolation cluster reaches more than 83% at the melting point (T-m) to form a liquid phase. These results show previously unreported aspects of the glass-to-liquid transition and share some trends observed for homogeneous melting of crystalline solids without a free surface.