Collapse of Stiff Polyelectrolytes due to Counterion Fluctuations

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Abstract
The effective elasticity of highly charged stiff polyelectrolytes is studied in the presence of counterions, with and without added salt. The rigid polymer conformations may become unstable due to an effective attraction induced by counterion density fluctuations. Instabilities at the longest (intermediate) length scales may signal a collapse to globule (necklace) states, respectively. In the presence of added salt, a generalized electrostatic persistence length is obtained, which has a nontrivial dependence on the Debye screening length.