Conformational statistics of ribbonlike semiflexible polymer chains

The conformational statistics of ribbonlike polymers possessing bending and twist rigidity are considered on the basis of a lattice model of directed self-correlated walks. It was assumed that local properties of the ribbonlike chain are strongly anisotropic: bending is possible only in the plane of the ribbon (the orientation of this plane can vary due to twist). The generating function for the distribution of a chain segment that is non-Gaussian is constructed. It is shown that in the isotropic environment the twist degree of freedom has no effect on the state of such macromolecules as a whole, and the consideration of rigidity alone in bending results in correct statistical features of a polymer chain. This model is suitable in accounting for the twist degree of freedom in the system with broken rotary symmetry.