Theory of long-time wave number dependent diffusion coefficients in concentrated neutral colloidal suspensions

We present for the first time a theory for the long-time wave number (k-) d ependent collective ana self-diffusion coefficients D-L(k, phi) and D-S(L)( k, phi), respectively, of neutral colloidal suspensions at high volume frac tions phi. This theory is based on the Smoluchowski equation with mean-fiel d-like hydrodynamic interactions, cage-diffusion and is free of adjustable parameters. The results provide a molecular interpretation of the experimen ts by Segre et al. (SEGRE P. N. and PUSEY P. N., Phys. Rev. Lett., 77 (1996 ) 771), who recently measured D-L(k, phi) of a concentrated neutral colloid al suspension.