Dynamics of wormlike chains: theory and computer simulations

Sergio Ramiro Aragon; Rolland Luo

doi:10.1117/12.44157

1 June 1991 Dynamics of wormlike chains: theory and computer simulations

Sergio Ramiro Aragon, Rolland Luo

Proceedings Volume 1430, Photon Correlation Spectroscopy: Multicomponent Systems; (1991) https://doi.org/10.1117/12.44157
Event: Optics, Electro-Optics, and Laser Applications in Science and Engineering, 1991, Los Angeles, CA, United States

Abstract

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.

Citation Download Citation

Sergio Ramiro Aragon and Rolland Luo "Dynamics of wormlike chains: theory and computer simulations", Proc. SPIE 1430, Photon Correlation Spectroscopy: Multicomponent Systems, (1 June 1991); https://doi.org/10.1117/12.44157

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