The stochastic motions in stable and bistable potentials are compared
on the basis of a Langevin-like equation with a deterministic (chaotic
) process replacing Gaussian white noise. Ergodic and mixing propertie
s are obtained under rather general circumstances. In the case of the
symmetric double-well potential, the system exhibits a behavior, quite
different from what one observes for stable potentials: as the contro
l parameters are varied, the system undergoes a phase transition from
an ergodic to a nonergodic phase. Lyapunov exponents and fractal dimen
sions are studied for more detailed insight.