Diffusion in the presence of random fields and transition rates: Effect of the hard-core interaction

We study diffusion of hard-core particles in linear chains where disorder arises from two distinct sources, (i) random bias fields and (ii) random transition rates. In the case of random bias fields, the step probability to the left and right is randomly chosen to be (1+E)/2 and (1-E)/2 with equal probability. Using Monte Carlo simulations and scaling arguments we find that the mean-square displacement is given by x2(t)[A(c)(lnt)]4, and the probability density P(x,t) scales as P(x,t)<x2(t)>-1/2G(x/x2(t)>1/2). Here c is the concentration of particles; for c0 x2(t) reduces to the Sinai result for noninteracting particles. We find that the scaling function G(u) has the form G(u)exp(-u), with =1.5, a value distinctly different from the value for noninteracting particles (=1.25) and from the value for zero-bias field (=2). In contrast, in the case of random transition rates with a power-law distribution, we find that the asymptotic behavior of x2(t) as well as P(x,t) is changed by the hard-core interaction.