Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 3: Membranes and Interfaces

BP 3.9: Talk

Monday, March 26, 2007, 16:15–16:30, H43

Interplay of lateral diffusion and membrane fluctuations — •Ellen Reister-Gottfried and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany

Using a simulation scheme that numerically integrates both the equation of motion of a membrane and the Langevin equation of a particle diffusing freely along the curved surface of the membrane we study the interplay of membrane fluctuations and lateral diffusion. The energy of the membrane is given by the Helfrich Hamiltonian and its shape in the Monge gauge. In the regime where the relaxation time of membrane undulations with wavelength ξ is much smaller than the average time it takes a particle to cover the distance ξ, the particle experiences only averaged membrane quantities, such that a preaveraging approximation can be employed. We compare the diffusion coefficient projected on a flat reference plane –this is the typically measured quantity– obtained in previous analytical calculations that make use of this approximation with simulation results. Although the simulation scheme overcomes preaveraging, there is a surprisingly good agreement of analytical and simulation results even for parameter sets that do not meet the conditions for the preaveraging approximation. A detailed analysis of appropriate correlation functions using the simulation scheme explains the large validity range of the approximation.