98-598 A. Asselah (asselah@math.ethz.ch), R. Brito, (brito@seneca.fis.ucm.es), J. L. Lebowitz, (lebowitz@math.rutgers.edu)

Self-Diffusion in Simple Models: Systems with Long-Range Jumps (26K, Tex files and a ps file) Sep 11, 98

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Abstract. We review some exact results for the motion of a tagged particle in simple models. Then, we study the density dependence of the self diffusion coefficient, $D_N(\rho)$, in lattice systems with simple symmetric exclusion in which the particles can jump, with equal rates, to a set of $N$ neighboring sites. We obtain positive upper and lower bounds on $F_N(\rho)=N((1-\r)-[D_N(\rho)/D_N(0)])/(\rho(1-\rho))$ for $\rho\in [0,1]$. Computer simulations for the square, triangular and one dimensional lattice suggest that $F_N$ becomes effectively independent of $N$ for $N\ge 20$.

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