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Journal of Statistical Physics

, Volume 48, Issue 3–4, pp 709–726 | Cite as

Diffusion in a periodic Lorentz gas

  • Bill Moran
  • William G. Hoover
  • Stronzo Bestiale
Articles

Abstract

We use a constant “driving force”F d together with a Gaussian thermostatting “constraint force”F d to simulate a nonequilibrium steady-state current (particle velocity) in a periodic, two-dimensional, classical Lorentz gas. The ratio of the average particle velocity to the driving force (field strength) is the Lorentz-gas conductivity. A regular “Galton-board” lattice of fixed particles is arranged in a dense triangular-lattice structure. The moving scatterer particle travels through the lattice at constant kinetic energy, making elastic hard-disk collisions with the fixed particles. At low field strengths the nonequilibrium conductivity is statistically indistinguishable from the equilibrium Green-Kubo estimate of Machta and Zwanzig. The low-field conductivity varies smoothly, but in a complicated way, with field strength. For moderate fields the conductivity generally decreases nearly linearly with field, but is nearly discontinuous at certain values where interesting stable cycles of collisions occur. As the field is increased, the phase-space probability density drops in apparent fractal dimensionality from 3 to 1. We compare the nonlinear conductivity with similar zero-density results from the two-particle Boltzmann equation. We also tabulate the variation of the kinetic pressure as a function of the field strength,

Key words

Gaussian thermostat two-dimensional periodic Lorentz gas hard disks conductivity fractal 

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Copyright information

© Plenum Publishing Corporation 1987

Authors and Affiliations

  • Bill Moran
    • 1
  • William G. Hoover
    • 1
  • Stronzo Bestiale
    • 2
  1. 1.Lawrence Livermore National Laboratory, and Department of Applied ScienceUniversity of California at Davis-LivermoreLivermore
  2. 2.Institute for Advanced Studies at PalermoSicilyItaly

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