Crossover to potential energy landscape dominated dynamics in a model glass-forming liquid

An equilibrated model glass-forming liquid is studied by mapping successive configurations produced by molecular dynamics simulation onto a time series of inherent structures ~local minima in the potential energy!. Using this ‘‘inherent dynamics’’ approach we find direct numerical evidence for the long held view that below a crossover temperature, Tx , the liquid’s dynamics can be separated into ~i! vibrations around inherent structures and ~ii! transitions between inherent structures @M. Goldstein, J. Chem. Phys. 51, 3728 ~1969!#, i.e., the dynamics become ‘‘dominated’’ by the potential energy landscape. In agreement with previous proposals, we find that Tx is within the vicinity of the mode-coupling critical temperature Tc . We further find that near Tx , transitions between inherent structures occur via cooperative, stringlike rearrangements of groups of particles moving distances substantially smaller than the average interparticle distance. © 2000 American Institute of Physics. @S0021-9606~00!50122-6#