Statistical Mechanics of Semiflexible Chains: A Meanfield Variational Approach

We describe a simple meanfield variational approach to study a number of properties of intrinsically stiff chains which are appropriate models for a large class of biopolymers. We present the calculation of the distribution of end-to-end distance and the elastic response of stiff chains under tension using this approach. In the former example we find that the simple expression almost quantitatively fits the results of computer simulation. For the case of the stiff chain under tension we recover analytically all the known limits. We obtain quantitative agreement with recent experiments on the stretching of DNA. The limitations of our approach are also discussed.