Charge trapping in DNA due to intrinsic vibrational hot spots

We study temperature effects on the characteristic time for which charge carriers remain spatially confined while interacting with fluctuational openings (bubbles) of double stranded DNA. Using semiclassical molecular-dynamics simulations, we find that in the low-temperature regime this characteristic time decreases in a power-law fashion with temperature and coincides with the polaronic lifetime. However, above 50-70 K the confinement time exhibits an exponential increase with temperature. We demonstrate that this enhanced trapping is a result of intrinsic dynamical structural disorder resulting from thermal fluctuations. Specifically, nonlinearity-induced hot spots in the lattice subsystem form breathing potential barriers confining the charge for substantially longer times. (C) 2003 American Institute of Physics.