VISCOELASTIC PROPERTIES OF SEMIFLEXIBLE MACROMOLECULES IN SOLUTION - BROWNIAN DYNAMICS SIMULATION OF A TRUMBBELL MODEL

The viscoelastic behavior of semiflexible macromolecules is studied us ing a trumbbell model with variable flexibility at the central hinge. The frequency-dependent solution viscosity for that model is calculate d from Brownian dynamics simulations. The Green-Kubo formula is used t o calculate the viscosity from flow-free Brownian trajectories. First, we obtain overall macromolecular properties such as the zero-shear in trinsic viscosity, longest relaxation times for viscoelasticity and fo r reorientation of the end-to-end vector, and others. We also calculat e curves for the frequency dependence of the dynamic moduli. The resul ts are compared with the existing theories of Roitman and Zimm and of Nagasaka and Yamakawa. Of particular interest is the determination of the range of flexibility for which the latter (which includes the effe cts of hydrodynamic interaction) is valid. Finally, we discuss the way in which hydrodynamic interaction influences the viscoelastic behavio r of semiflexible macromolecules.