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CPM Seminar
James Polson
Physics Department The collapse of a single polymer chain from a conformationally extended coil in `good' solvent conditions to a compact `globule' in `poor' solvent conditions has been one of the most extensively studied topics in theoretical polymer physics. A key reason for this interest is its close relation to protein folding, one of the most important problems in molecular biology. The overwhelming majority of work on the polymer collapse transition has focused on the equilibrium properties of the transition, and, consequently, a detailed understanding of the relationship between equilibrium polymer size and solvent quality is now available. On the other hand, a clear picture of the nature of the collapse dynamics has yet to emerge. Beginning with the work of de Gennes in 1985, several theories of collapse dynamics have been developed, including both phenomenological theories, and others based on an analysis of the Langevin equation. Generally, it is recognized that solvent-mediated hydrodynamic interactions will play an important role. On the other hand, most simulation studies tend to employ models which ignore the explicit presence of the solvent. While this greatly improves computational effeciency, important qualitative solvent effects are likely to be absent or distorted. Thus, a much better description of the solvent in polymer collapse simulations is essential in order to interpret experimental data and test analytical theories. In this talk, I review recent experimental, theoretical and simulation studies of polymer collapse dynamics. I present recent simulation work on explicit-solvent model systems and emphasize the importance of solvent-mediated effects on the equilibrium properties and dynamics of the collapse transition. I conclude the talk with a critical discussion of alternative simulation approaches in which the solvent can be included by employing models which retain the hydrodynamic effects, yet which can be implemented in a much more computationally efficient manner than the simple explicit-solvent approach.
Monday, October 22nd 2001, 12:00 |