Abstract: The folding dynamics of a completely stretched dexoxyribonucleic acid (DNA) molecule chain is an important feature of single DNA mechanics. By constructing a fully parameterized bead-spring chain model and applying a highly efficient second order semi-implicit predictor-corrector algorithm, we studied the influence of three nonlinear interactions including the excluded volume interaction, the finite extensible nonlinear elastic interaction, and the fluctuating hydrodynamic interaction on the folding process. Simulation results show that the excluded volume interaction decreases the relative radius of gyration of the DNA chain obviously but has no influence on the relaxation time. Instead, the hydrodynamic interaction clearly decreases the relaxation time but it does not change the relative radius of gyration. In addition, the finite extensible elastic interaction was found to decrease the relative radius of gyration of the short chain clearly and increase the relaxation time of the long chain obviously. Furthermore, we obtained a smooth change for the relative radius of gyration with time. The scaling exponent of the relaxation time with the length of chain has two different values under all three nonlinear interactions. These results complete our understanding about single DNA molecule chain mechanics in solution.

Key words: Single DNA molecule chain, Bead-spring model, Nonlinear interaction, Brownian dynamics simulation, Folding process