Large Long-Time Tails and Shear Waves in Dense Classical Liquids

The apparently large long-time-tail contribution to the stress-tensor autocorrelation function observed in computer simulations is explained on the basis of a generalized modecoupling theory. This theory includes effects that occur on a molecular length scale where structural relaxation is important. These structural effects are also shown to be responsible for the appearance of propagating shear waves in dense liquids at large wave numbers.