Macromolecular self-diffusion and momentum autocorrelation functions in dilute solutions

We use an improved version of the solution to the one particle generalized Smoluchowski equation found earlier to calculate the self-diffusion coefficient D and the long time behavior of the momentum autocorrelation function φ (t) for a dilute system of uncharged, spherical macromolecules in solution. For D we find the infinite dilution result which is consistent with other theories based on Oseen’s model which we also use; our calculation does eliminate some other assumptions which are used in previous calculations. The asymptotic decay of φ (t) is found to be algebraic, as t−5/2; the −5/2 exponent is probably due to the use of Oseen’s model, and for a higher order hydrodynamic theory which gives a nonvanishing o (c) contribution to D we expect that φ (t) will decay as t−3/2.