We have extended the beadndash;spring model of Zimm to include hydrodynamic interaction that depends upon the conformation of the polymer and hence the deformation rate. Our computational scheme is based on the model of Fixman, and it allows us to investigate numerically chains as large as 500 beads. The major approximation is the replacement of the hydrodynamic interaction tensor with its configurational average. We find that the incorporation of configurationhyphen;dependent hydrodynamic interaction qualitatively changes the Zimm predictions for both the shear and the elongational viscosity. In particular, the elongational viscosity becomes a multivalued function of the rate of elongation. This result is consistent with the coilhyphen;tohyphen;stretch transition predicted by de Gennes and Hinch.
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