Free energy of deformation of the radius of gyration in semiflexible chains

Abstract

The distribution function P(S) of the radius of gyration S, the corresponding elastic free energy A(S) and the mean force 〈f〉 (S) were computed from simulations based on the wormlike chain (WLC) model. The relation of the S-conjugated elastic functions to the analogous functions based on the chain vector R and their connection to the statistical-mechanics ensembles was elucidated. Simulation data revealed that available analytical functions for P(S) fail to predict the behavior of semiflexible chains. When the power-law function P(S) was used instead, the exponents sizeably raised with stiffness at chain expansion. The exponents deduced from elastic compression of a chain agreed fairly with the scaling exponents for chain confinement into a sphere. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.