Classical Diffusion on a Random Chain

A simple model of classical diffusion on a random chain is studied. The velocities to the right and to the left are calculated. When one changes continuously the probability distribution ρ of the hopping rates, a whole region is found where these two velocities vanish. In this region, the distance R covered by a particle during the time t behaves like R~tˣ, where x depends continuously on ρ. The exponent x is calculated for a simple example.