Persistence lengths of semiflexible chains — methods and approximations

Abstract Several models and methods for stiff polymer chains are discussed. The basic idea is to develop approximate solutions to the problem of the presistence length of stiff polymers. It turns out that the persistence length can be regarded as a measure for the quality of approximations. Mean‐field methods for field theoretical calculations of the persistence length show similarities of 1/ d expansions in statistical physics ( d being the space dimension) and saddle point approximations become reliable in various limits. Gaussian approximations become — as well known for the Ising model — simple extensions of random walks as trivial renormalisations of the Wiener‐Edwards model for bosonic strings.