Programme

I.2 -- Invited, NCTP-39

Date: Wednesday, 30-07-2014

Time: 08h30 - 09h00

Elasticity, long-range interactions and the toroidal condensate of semiflexible polymers

Trinh Xuan Hoang, Trinh Lan Hoa, Nguyen Thanh Hai

Institute of Physics, Vietnam Academy of Science and Technology, Hanoi, Vietnam

We consider various forms of the elastic bending energy, surface potential and long range interactions between segments for semiflexible polymers and study the competition between the toroidal and the rod-like conformations as possible ground states of DNA in a bad solvent. The long-range interactions driving the DNA condensation are assumed to be of the form pertaining to the attractive depletion potential as well as the attractive counterion induced soft potential. In the stiffness-length plane we find a transition from rod-like to toroid condensates for increasing stiffness at a fixed chain length $L$. The transition line is found to have a $L^{\lambda}$ dependence where the exponent $\lambda$ depends solely on the form of the elastic potential ($\lambda=1/3$ for the worm-like chain), and does not depend on the details of the long-range interaction between neighboring segments. We also find a complete disappearance of the rod-like condensate for any chain length when the elastic potential is sufficiently soft. When realistic DNA parameters are used, our description reproduces rather well some of the experimental features observed in DNA condensates.

Presenter: Trịnh Xuân Hoàng