Regensburg 2013 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 33: Poster II

DY 33.12: Poster

Thursday, March 14, 2013, 17:00–19:00, Poster C

Dynamic scaling of a critical binary mixture — Dipanjan Chakraborty, •Felix Höfling, and Siegfried Dietrich — Max Planck Institute for Intelligent Systems, Stuttgart, andInstitute for Theoretical Physics IV, Universität Stuttgart, Germany

A binary mixture near its consolute point exhibits critical fluctuations of the local composition. The static properties of the mixture are well described by the Ising universality class in three dimensions [1], the dynamic properties involving conservation of particles, energy, and momentum are classified as “model H”. So far, theoretical work on the critical dynamics has focused mainly on transport coefficients, while studies of the relaxation dynamics of the spatially resolved order parameter have remained elusive.

We present numerical results for the dynamic structure factor of a symmetric binary Lennard-Jones mixture near its demixing transition. To this end, we have performed extensive molecular dynamics simulations in the microcanonical ensemble, employing the immense computing resources of high-end graphics processors [2]. Our simulations cover large systems of 70,000 particles and more than 4 non-trivial orders of magnitude in time. We explore the crossover of the wavenumber-dependent relaxation time from diffusion-like to critical behaviour and find nice agreement with theoretical predictions. Further, dynamic scaling of the full time dependence of the critical relaxation is tested and dynamic scaling functions are deduced.

[1] S. K. Das et al., J. Chem. Phys. 125, 024506 (2006)

[2] P. Colberg and F. Höfling, Comp. Phys. Comm. 182, 1120 (2011)