Breakdown of the Stokes–Einstein relation in supercooled liquids

The Stokes–Einstein and Stokes–Einstein–Debye relations hold well in nonsupercooled liquids; however, sizeable deviations from the former appear in supercooled liquids, leading to a ‘‘decoupling’’ of translational diffusion from viscosity and reorientational relaxation. We attribute this breakdown and this ‘‘decoupling’’ to the existence of structured domains in the supercooled liquid.