Evidence for a Dynamical Crossover in a Supercooled Liquid from Analysis of its Potential Energy Landscape

We map the dynamics of a supercooled liquid to transitions between successive potential energy basins. In terms of the self intermediate scattering function, $F_s(q,t)$, we demonstrate that the separation of the system's dynamics into (i) vibrations within potential energy basins and (ii) transitions between them, becomes valid as a crossover temperature, $T_x$, is approached. Our results support the previously proposed identification of $T_x$ with the mode coupling critical temperature, $T_c$. Preliminary results indicate that transitions between inherent structures at $T>T_c$ involve cooperative particle motion.