In this paper,we study nonlinear Kramers problem by investigating overdamped systems ruled by the one-dimensional nonlinear Fokker-Planck equation.We obtain an analytic expression for the Kramers escape rate under quasistationary conditions by employing a metastable potential and its predictions are in excellent agreement with numerical simulations.The results exhibit the anomalies due to the nonlinearity in W that the escape rate grows with D and drops as mu,becomes large at a fixed D.Indeed,particles in the subdiffusive media (mu > 1) can escape over the barrier only when D is above a critical value,while this confinement does not exist in the superdiffusive media (mu < 1).
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