     Next: Appendix A Up: The Zimm chain Previous: Normal coordinates and the

# Diffusion coefficient and viscosity

The diffusion coefficient  of a Zimm chain can be easily calculated from Eqs. (7.16) and (7.17). The result is

 DG = (7.19)  (7.20) = (7.21)

The diffusion coefficient now scales with N-1/2, in agreement with experiments.

In order to calculate the intrinsic viscosity  of a dilute solution of Zimm chains we go back to Eq. (6.64): (7.22)

Again we shall approximate by its equilibrium value. At the end of this section we shall show that (7.23)

The solution of Eq. (7.22) with this approximation is (7.24)

Eqs. (6.53), (6.57) and (7.24) then yield (7.25)

The intrinsic viscosity scales with N3/2, in agreement with experiments.

We finish this section by proving Eq. (7.23). At equilibrium we have

 0 = (7.26) = (7.27)

The last term here can be calculated according to = (7.28) = (7.29)

Eq. (7.27), (7.29) and (7.17) yield Eq. ( 7.23).     Next: Appendix A Up: The Zimm chain Previous: Normal coordinates and the
W.J. Briels