α-relaxation spectra in supercooled liquids

The shape of the α-relaxation spectra in supercooled liquids is discussed within the mode-coupling approach. The dynamical behaviour is ruled by properties of various bifurcation singularities in the non-linear equations of motion. The stretched exponential behaviour appears as the generic case, and is intimately related with the von Schweidler relaxation. The theory can also account for a double α, α′ peak scenario which is related to self-intersections of the bifurcation hypersurface. The cusp singularities are also briefly discussed and they can account for complex spectra which are observed in many polymeric systems.