Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Focus Session: Computational Polymer Physics - New Developments (jointly with CPP)

DY 24.3: Hauptvortrag

Mittwoch, 16. März 2011, 15:00–15:30, MOL 213

Mechanical separation of short double stranded DNA: Effect of pulling geometry — •Sanjay Kumar — Department of Physics, Banaras Hindu University, Varanasi 221 005, India

Using the Exact Enumeration technique and Molecular Dynamics simulation, we study the influence of force on the melting of DNA. A force is applied perpendicular to the helix direction to study the DNA unzipping. The force-temperature diagram is consistent with the experiment but differs significantly with the theoretical predictions. However, when a force is applied along the helix direction, we have a situation similar to the DNA rupture. We show that the rupture force increases linearly with the chain length and approaches to the asymptotic value. This is consistent with the experiment. We also observed that the rupture force depends logarithmically on the loading rate. It was found that below a certain loading rate, rupture force decreases with temperature, whereas above it, increases with temperature. Using phenomenological argument, we explain why the rupture force has distinctively different behavior for two temperatures above and below a certain loading rate. We substantiate our argument with the simulation.