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 serie s of inherent structures (local minima in the potential energy). Using this "inherent dynamics" approach we find direct numerical evidence for the lon g held view that below a crossover temperature, T-x, the liquid's dynamics can be separated into (i) vibrations around inherent structures and (ii) tr ansitions between inherent structures [M. Goldstein, J. Chem. Phys. 51, 372 8 (1969)], i.e., the dynamics become "dominated" by the potential energy la ndscape. In agreement with previous proposals, we find that T-x is within t he vicinity of the mode-coupling critical temperature T-c. We further find that near T-x, transitions between inherent structures occur via cooperativ e, stringlike rearrangements of groups of particles moving distances substa ntially smaller than the average interparticle distance. (C) 2000 American Institute of Physics. [S0021-9606(00)50122-6].