PERSISTENCE LENGTH OF POLYELECTROLYTE CHAINS

The classical theory of the electrostatic persistence length of polyel ectrolyte chains due to Odijk, Skolnick and Fixman (OSF) is revisited. In contrast to the original theory, our approach takes into account t he effect of fluctuations in the chain configuration. As a result, we find that the OSF theory, although correct for intrinsically rigid pol yelectrolytes, breaks down for flexible chains. A quantitative criteri on is established to distinguish between flexible and rigid chains. Fo r flexible chains, we use a variational theory to compute the electros tatic persistence length, which is found to be proportional to the Deb ye-Huckel screening length, in agreement with many experimental and si mulation results.