Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 4: SYMPOSIUM: Dynamics of multi-component fluids IV
CPP 4.3: Vortrag
Freitag, 4. März 2005, 16:30–16:45, TU C243
Computer simulations of ethanol/water mixtures - from the atomistic to the mesoscale — •Jörg R. Silbermann, Sabine H. L. Klapp, and Martin Schoen — Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin, Straße des 17. Juni 124, D-10623 Berlin, Germany
We consider fluid mixtures of ethanol (E) dissolved in water. Atomistic simulations(1) permit us to extract the center of mass (cm) pair distribution function gEE(R) of the ethanol molecules. Based on gEE(R) we seek for an effective pair potential UEE(R) capable of describing the system on a mesoscopic scale, where the solvent is no longer treated explicitly and the ethanol molecules are represented by isotropic beads. Using mesoscale computer simulations, we study this issues for several compositions of the mixture. At small ethanol densities the potential of mean force Umf(R)=−kTlngEE(R) turns out to reproduce the atomistic gEE(R) in a satisfactory way, indicating that three- and more-body interactions are negligible. For systems with larger ethanol densities, however, corrections for higher order interactions are nessecary. In this context we investigate the capabilities of integral equation techniques to extract UEE(R). Moreover, we investigate prospects to recover the dynamics of the prestine system on a mesoscopic scale by means of dissipative particle dynamics concepts.
(1)N. Chennamsetty, H. Bock, K. E. Gubbins, Department of Chem. Engineering, NC State University