Inherent-structure dynamics and diffusion in liquids - art. no. 032201

The self-diffusion constant D is expressed in terms of transitions among th e local minima (inherent structures, IS) of the N-body potential-energy sur face or landscape, and their correlations. The formulas are evaluated and t ested against simulation in the supercooled, unit-density Lennard-Jones liq uid. The approximation of uncorrelated IS-transition (IST) vectors Do, grea tly exceeds D for the highest T, but merges with simulation at reduced T si milar to 0.50, close to the estimated mode-coupling temperature T-c. Since uncorrelated IST's are associated with a hopping mechanism, the condition D similar to D-o provides a new way to identify the crossover to hopping. Th e results suggest that theories of diffusion in deeply supercooled liquids may be based on weakly correlated IST's.