minimum of $c(x)$.[]{data-label="uni"}](figure6.eps){width="3in"}

We should note that the minimal critical value $\varkappa_c$ according to is $1/2$. Remember, however, that here we consider the second mechanism of the breakdown of the normal diffusion (i.e., the singularity of $Z_4(x,y,z)$). For the mechanism I (the superlinear growth of the integral (\[lin\])) the breakdown takes place for the arbitrary small $\varkappa$ if the correlation function decays slow enough.

Experimental evidence for the breakdown of the normal diffusive transport
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Our main result shows that the nondispersive transport regime for the spatially correlated exponential DOS demonstrates very rich behavior not restricted to the trivial case of the normal diffusion. For various types of the correlation function $c(x)$ the diffusivity does not exist for sufficiently low temperature (though still in the region $U_0/kT < 1$) and spreading of the carriers’ packet does not follow usual diffusive law $\Delta x\propto t^{1/2}$. This observation gives a possibility to provide an experimental test of the transition to the anomalous diffusion using the time-of-flight experiment in amorphous organic semiconductors. For the quasi-equilibrium nondispersive transport a typical photocurrent transient demonstrates initial drastic decrease of the current, associated with the spatial and energetic relaxation of the carriers, then development of the plateau 