Aspects of the dynamics of colloidal suspensions: Further results of the mode coupling theory of structural relaxation

Results of the idealized mode-coupling theory for the structural relaxation in suspensions of hard-sphere colloidal particles are presented and discussed with regard to recent light scattering experiments. The structural relaxation becomes nondiffusive for long times, contrary to the expectation based on the de Gennes narrowing concept. A semiquantitative connection of the wave vector dependences of the relaxation times and amplitudes of the final alpha relaxation explains the approximate scaling observed by Segre and Pusey [Phys. Rev. Lett. 77, 771 (1996)]. Asymptotic expansions lead to a qualitative understanding of density dependences in generalized Stokes-Einstein relations. This relation is also generalized to nonzero frequencies thereby yielding support for a reasoning by Mason and Weitz [Phys. Rev. Lett. 74, 1250 (1995)]. The dynamics transient to the structural relaxation is discussed with models incorporating short-time diffusion and hydrodynamic interactions for short times. [S1063-651X(99)05311-8].