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Iowa State University

2000

Beate Schmittmann

Articles 1 - 3 of 3

Full-Text Articles in Physics

Viability Of Competing Field Theories For The Driven Lattice Gas, Beate Schmittmann, H. K. Janssen, U. C. Tauber, R. K. P. Zia, K.-T. Leung, J. L. Cardy May 2000

Viability Of Competing Field Theories For The Driven Lattice Gas, Beate Schmittmann, H. K. Janssen, U. C. Tauber, R. K. P. Zia, K.-T. Leung, J. L. Cardy

Beate Schmittmann

It has recently been suggested that the driven lattice gas should be described by an alternate field theory in the limit of infinite drive. We review the original and the alternate field theory, invoking several well-documented key features of the microscopics. Since the alternate field theory fails to reproduce these characteristics, we argue that it cannot serve as a viable description of the driven lattice gas. Recent results, for the critical exponents associated with this theory, are reanalyzed and shown to be incorrect.


Universal Aspects Of Vacancy-Mediated Disordering Dynamics: The Effect Of External Fields, Wannapong Triampo, Timo Aspelmeier, Beate Schmittmann Mar 2000

Universal Aspects Of Vacancy-Mediated Disordering Dynamics: The Effect Of External Fields, Wannapong Triampo, Timo Aspelmeier, Beate Schmittmann

Beate Schmittmann

We investigate the disordering of an initially phase-segregated binary alloy, due to a highly mobile defect which couples to an electric or gravitational field. Using both mean-field and Monte Carlo methods, we show that the late stages of this process exhibit dynamic scaling, characterized by a set of exponents and scaling functions. A new scaling variable emerges, associated with the field. While the scaling functions carry information about the field and the boundary conditions, the exponents are universal. They can be computed analytically, in excellent agreement with simulation results.


Field-Induced Vacancy Localization In A Driven Lattice Gas: Scaling Of Steady States, M. Thies, Beate Schmittmann Jan 2000

Field-Induced Vacancy Localization In A Driven Lattice Gas: Scaling Of Steady States, M. Thies, Beate Schmittmann

Beate Schmittmann

With the help of Monte Carlo simulations and a mean-field theory, we investigate the ordered steady-state structures resulting from the motion of a single vacancy on a periodic lattice which is filled with two species of oppositely “charged” particles. An external field biases particle-vacancy exchanges according to the particle’s charge, subject to an excluded volume constraint. The steady state exhibits charge segregation, and the vacancy is localized at one of the two characteristic interfaces. Charge and hole density profiles, an appropriate order parameter, and the interfacial regions themselves exhibit characteristic scaling properties with system size and field strength. The lattice …