A statisticalhyphen;mechanical theory of wormlike chains with helical conformations arising from bending and torsional energies is developed. A differential equation for the trivariate distribution function of the endhyphen;tohyphen;end distance, the unit tangent vector, and the unit curvature vector is derived from the path integral formulation, and several moments are evaluated. The results show that the characteristic ratio for the endhyphen;tohyphen;end distance or the radius of gyration as a function of chain lengthtexhibits a maximum with a swelling at sometgreater than the maximum point under certain conditions. It is applied to atactic and syndiotactic poly(methylmethacrylate) chains, and their helix parameters are determined reasonably. The theory is also applied to the helixndash;coil transition in polypeptide chains.
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