Chain dynamics and power-law distance fluctuations of single-molecule systems.

Chain-dynamics-induced distance fluctuations between any two points in a finite chain with or without cross links are investigated. This model leads to three regimes of temporal behavior for distance autocorrelation: (i) initial flat time dependence, (ii) t(-alpha) power law, and (iii) long-time exponential decay. For an ideal Rouse chain with frequency-independent friction, alpha = 1/2. The span of the characteristic power-law behavior of a long chain could be reduced significantly with the presence of cross links.