Research Activities > Programs > Complex Fluids 2007

Computer simulations of critical dynamics in fluids

CSIC Building (#406), Seminar Room 4122.
Directions: home.cscamm.umd.edu/directions


Computer simulations of critical dynamics in fluids

 

Professor Jan V. Sengers

University of Maryland


Abstract:   The static and dynamic behavior of systems is known to become singular near critical points. As explained by the renormalization-group theory of critical phenomena, this singular behavior finds its origin in the presence of fluctuations at all length scales, from microscopic to mesoscopic. During the past decade considerable progress has been made in simulating critical fluctuations in fluids and fluid mixtures with computers. Thus accurate numerical data have been obtained for the thermodynamic behavior of fluids near critical points
Computer simulations of critical dynamics, however, appear to be more challenging for two reasons. First, the fluctuations exhibit an anomalous critical slowing down that is intimately related to the so-called long-time-tail behavior of the dynamic correlation functions. As a consequence, finite-size effects are even more significant than in computer simulations of equilibrium critical properties and turn out to be more pronounced. Second, one needs to carefully distinguish between the decay of short-range fluctuations versus the decay of long-range fluctuations.
We shall present computer simulations of critical dynamics in a mixture of Lennard-Jones liquids. It will be shown how a proper finite-size analysis of the simulation data can account for the phenomena mentioned above, leading to physically reliable results completely consistent with the theoretical predictions from mode-coupling theory and with experimental evidence, thus validating molecular-dynamics simulations as a new procedure for studying critical dynamics.

*Research performed in collaboration with S.K. Das and M.E. Fisher at the University of Maryland and with J. Horbach and K. Binder at the Johannes Gutenberg Universitšt Mainz, Germany.

References:
S.K. Das, M.E. Fisher, J.V. Sengers, J. Horbach. and K. Binder, Phys. Rev. Lett. 97, 025702 (2006).
S.K. Das, J. Horbach, K. Binder, M.E. Fisher, and J.V. Sengers, J. Chem. Phys. 125, 024506 (2006).
[slides]

University of Maryland    

UM Home | Directories | Calendar
Maintained by CSCAMM
Direct questions and comments to

CSCAMM is part of the
College of Computer, Mathematical & Natural Sciences (CMNS)