The frequency dependence of jump conduction

Current relaxation and the frequency dependence of the jump conduction have been examined via percolation arguments and hypothesis on the behavior of the correlation length near the threshold corresponding to the formation of an infinite bond cluster. It is shown that the relaxation at large times and the frequency dependence of the conduction over a wide frequency range are governed by a universal function that is the solution to a transcendental equation whose only parameter is a critical value. This function is of power-law type over a restricted frequency range, and the exponent varies between 0.5 and 1.