Excess of low-frequency modes in Lennard-Jones systems

Argon dynamics is simulated in the glassy state at the temperature of 20 K. A fast quenching is used to study the slow time evolution from the glass to the crystalline state. Observation of the crystallization process reveals the growth of temperature, a rapid change in the mean square displacement, and strong variations in the relative pair dynamics. Our main results are: (a) detecting the presence of a low-frequency mode in the pair dynamics of the glass; (b) showing that this mode is responsible for the intensity excess at low frequency in the power spectrum (compared to that of the crystal); and (c) showing that it decreases more and more as the crystallization proceeds.