Communications Project

Document Type:Master's Thesis
Name:Michael Thies
Title:Scaling of Steady States in a Simple Driven Three-State Lattice Gas
Degree:Master of Science
Committee Chair: Beate Schmittmann
Committee Members:Royce K.P. Zia
James R. Heflin
Keywords:Driven Lattice Gas, Scaling, Monte Carlo Simulation, Mean-Field Theo ry
Date of defense:September 9, 1998
Availability:Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.


Phase segregated states in a simple three-state stochastic lattice gas are investigated. A two dimensional finite lattice with periodic boundary conditions is filled with one hole and two oppositely "charged" species of particles, subject to an excluded volume constraint. Starting from a completely disordered initial configuration, a sufficiently large external "electric" field E induces the phase segregation, by separating the charges into two strips and "trapping" the hole at an interface between them. Focusing on the steady state, the scaling properties of an appropriate order parameter, depending on drive and system size, are investigated by mean-field theory and Monte Carlo methods. Density profiles of the two interfaces in the ordered system are studied with the help of Monte Carlo simulations and are found to scale in the field-dependent variable, 2 tanh (E/2), for E < 0.8. For larger values of E, independent approximations of the interfacial profiles, obtained within the framework of mean-field theory, exhibit significant deviations from the Monte Carlo data. Interestingly, the deviations can be reduced significantly by a slight modification of the mean-field theory.

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