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SYMP: Symposium Computational Soft matter physics

SYMP 2: Computational soft matter physics

SYMP 2.4: Hauptvortrag

Donnerstag, 28. Februar 2008, 15:30–16:00, H 0105

Simulation of coarse-grained membrane models — •Marcus Müller — Institut für Theoretische Physik, Georg-August Universität, Göttingen

Collective processes in membranes – like pore formation in membranes under tension or fusion of two apposed bilayers – exhibit a large degree of universality, i.e., similar phenomena are observed in systems that significantly differ in their microscopic interactions. Since these phenomena involve length scales of micrometers and time scales of milliseconds, they are difficult to study by atomistic simulations, but minimal coarse-grained models can provide detailed and direct insights into the molecular mechanisms.

An advantage of coarse-grained models is the calculation of free energies of self-assembled structures. This can be accomplished either by mapping the model onto molecular field theories and using the mean field approximation or by special simulation techniques. In the latter case, applying an external, ordering field, one imposes a pre-defined structure onto the fluid in the disordered phase (e.g., at high temperature). This structure closely resembles the self-assembled structure (at low temperature, in the absence of an ordering field). Subsequently, one gradually switches off the external, ordering field and, in turn, increases the control parameter (temperature) that drives the self-assembly. The free energy difference along this reversible path is obtained via thermodynamic integration or expanded ensemble simulation techniques.