ICMCS Seminar - Statistical Mechanics of DNA beyond the Wormlike Chain Model

The Wormlike Chain (WLC) model has long provided a remarkably successful description of DNA mechanics, accurately capturing its elastic response at large length scales and under weak deformations. However, growing experimental and computational evidence indicates that important features of DNA behavior lie beyond the assumptions of a purely local and harmonic elastic rod.

In this talk, I will discuss two classes of effects that extend the traditional WLC framework. First, non-local couplings along the DNA contour introduce a scale-dependent elastic response, leading to effective mechanical properties that vary with the observation length scale. Second, anharmonic elastic contributions become relevant under strong bending deformations and give rise to localized, highly curved configurations, often referred to as DNA kinks. These rare but mechanically important events can significantly alter the statistics of bending fluctuations and cyclization at short length scales.

Using detailed all-atom molecular dynamics simulations, we examine the microscopic origins of these phenomena and characterize their signatures in DNA conformational fluctuations. The simulations provide direct evidence for both scale-dependent elasticity and kink formation, offering a quantitative route to connect molecular interactions with coarse-grained descriptions of DNA mechanics. Together, these results highlight the limitations of the classical Wormlike Chain model and suggest new directions for the statistical-mechanical description of DNA across multiple length scales.

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