Conformations, transverse fluctuations, and crossover dynamics of a semi-flexible chain in two dimensions
Abbreviated Journal Title
J. Chem. Phys.
MONTE-CARLO-SIMULATION; DNA PERSISTENCE LENGTH; POLYMER-CHAIN; BROWNIAN; DYNAMICS; MONOMER DYNAMICS; EXCLUDED-VOLUME; MODEL; MACROMOLECULES; MICROSCOPY; STATISTICS; Physics, Atomic, Molecular & Chemical
We present a unified scaling description for the dynamics of monomers of a semiflexible chain under good solvent condition in the free draining limit. We consider both the cases where the contour length L is comparable to the persistence length l(p) and the case L >> l(p). Our theory captures the early time monomer dynamics of a stiff chain characterized by t(3/4) dependence for the mean square displacement of the monomers, but predicts a first crossover to the Rouse regime of t(2 nu/1 +) (2 nu) for tau(1) similar to l(p)(3), and a second crossover to the purely diffusive dynamics for the entire chain at tau(2) similar to L-5/2. We confirm the predictions of this scaling description by studying monomer dynamics of dilute solution of semi-flexible chains under good solvent conditions obtained from our Brownian dynamics (BD) simulation studies for a large choice of chain lengths with number of monomers per chain N = 16-2048 and persistence length l(p) = 1-500 Lennard-Jones units. These BD simulation results further confirm the absence of Gaussian regime for a two-dimensional (2D) swollen chain from the slope of the plot of < R-N(2)>/2Ll(p) similar to L/l(p) which around L/l(p) similar to 1 changes suddenly from (L/l(p)) -> (L/l(p))(0.5), also manifested in the power law decay for the bond autocorrelation function disproving the validity of the worm-like-chain in 2D. We further observe that the normalized transverse fluctuations of the semiflexible chains for different stiffness root < l(perpendicular to)(2)>/L as a function of renormalized contour length L/l(p) collapse on the same master plot and exhibits power law scaling root < l(perpendicular to)(2)>/L similar to (L/l(p))(eta) at extreme limits, where eta = 0.5 for extremely stiff chains (L/l(p) >> 1), and eta = -0.25 for fully flexible chains. Finally, we compare the radial distribution functions obtained from our simulation studies with those obtained analytically. (C) 2014 AIP Publishing LLC.
Journal of Chemical Physics
"Conformations, transverse fluctuations, and crossover dynamics of a semi-flexible chain in two dimensions" (2014). Faculty Bibliography 2010s. 5471.