Regensburg 1998 – scientific programme

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DY: Dynamik und Statistische Physik

DY 54: Fluide

DY 54.10: Talk

Friday, March 27, 1998, 12:45–13:00, H3

Thermo-Mechanical Properties of the WCA-Lennard-Jones
Model System in its Fluid and Solid States — •S. Hess¹, M. Kröger², and H. Voigt¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin — ²Polymer Physics, Institute of Polymers, ML H 18, Sonneggstr. 3, ETH Zentrum, CH-8092 Zürich

Thermo-mechanical properties of the WCA-Lennard-Jones model system in its fluid and fcc crystalline states are computed via Molecular Dynamics simulations, both with constant volume (NVT) and with constant pressure (NPT). Data for the pressure, energy, specific heat, bulk and shear elasticity coefficients, and for other quantities are presented as functions of the density, for a few selected temperatures. Those quantities which can be computed from the free energy, in the fluid state, are compared with theoretical expressions based on a modified Carnahan-Starling theory. This involves the second virial coefficient and a temperature dependent effective volume of a particle for which various expressions are discussed. Good agreement between theory and simulation is found for a simple specific choice of the effective volume. A simple equation of state is also presented for the Lennard-Jones-fluid.