The theory of the dynamics of wormlike chains based on the pure bending equation is reviewed. The normal mode solution obtained with the neglect of hydrodynamic interactions has been used to compute correlation functions for the forward depolarized dynamic light scattering, fluorescence polarization anisotropy, and the q dependent polarized dynamic light scattering of wormlike chains. The depolarized light scattering results are also applicable to the field free decay of the transient electric birefringence. Corrections to the relaxation rates due to hydrodynamic interactions are included. Extensive computer simulations based on Brownian dynamics for depolarized light scattering and fluorescence polarization anisotropy have been carried out with full and preaveraged hydrodynamic interaction, as a function of the ratio L/P of the contour length to persistence length of the chain. Flexibility was studied in the range 1 ≤ L/P ≤ 20 which spans relatively rigid to fairly flexible chains.
The simulations are compared to theory in order to.study the validity of the assumptions used.
It was found that the longest relaxation time observed in the simulations for all the
experiments could be interpreted as the rotational diffusion of the chain, in agreement with the
assumptions of the theory and the Yamakawa-Yoshisaki formulas for the rotational diffusion
coefficient, even in the very flexible case. In the case of fluorescence, the data may show the
presence of a small amount of coupling of flexing and rotation. The fast relaxation times in the rigid
region are also in good agreement with theory, but the analysis of the data for greater flexibilities is
not straightforward due to the resolution limitations of the exponential analysis programs and the
large number of relaxations that contribute. The simulations show that, in general, the coupling
between the degrees of freedom is small perhaps up to L/P ≤ 4, and is unknown beyond that. The
difference between full and preaveraged hydrodynamic interactions was systematic but small.