Translational friction coefficients of rigid, symmetric top macromolecules. Application to circular cylinders

Abstract

The hydrodynamic interaction equations and the interaction tensor that appear in the theoretical formalism for calculating translational friction coefficients of rigid particles modeled as assemblies of beads, are formulated in cylindrical coordinates. For symmetric top particles, the cylindrical shielding tensors of symmetry-equivalent beads are the same, and have only five nonzero components. This effects a great simplification with respect to the Cartesian formalism. Application is made to the end-effect correction, for translational motion of right circular cylinders modeled as stacks of rings, extrapolated to zero bead size. No appreciable changes in the translational friction coefficients are found when the hollow cylindrical models are capped at the ends with disc-shaped plates. For finite cylinders with axial ratio p≳2, our results, as well as those from other theoretical and experimental studies, are in remarkable disagreement with the previous calculations by Broersma.