Systematic Coarse-Graining of the Dynamics of Self-Attractive Semiflexible Polymers

We develop a coarse-graining procedure, using bead-rod chains with varying numbers of rods per Kuhn length (N-r,N-K), to model the conformational dynamics of polymer chains with bending stiffness and self-attraction. We find the conditions under which increased chain resolution leads to converged results for the effect of bending stiffness, attractive interaction strength (epsilon), and shearing flow on the conformational dynamics. As chain stiffness increases, we find a collapse transition that becomes steeper as attractive strength increases. The collapsed state depends not only on the net dimensionless attractive strength epsilon* = epsilon N-r,N-K between each Kuhn step of the chain but also on the ratio of bead diameter to Kuhn length (sigma*). At high epsilon* (>0.8/sigma*), collapsed globules are produced at moderate chain diameter sigma* = 1/4, while for fat chains with sigma* = 1, helices are formed, and for thin ones with sigma* = 1/16, tori, folded bundles, and finally globules are formed as epsilon* increases.