FRACTIONAL RELAXATION EQUATION FROM AC UNIVERSALITY IN DISORDERED SOLIDS

We derive a fractional relaxation equation in a setting which refers to the universal conductivity response of homogeneously disordered solid materials. Initial-time behavior of the decay function is a stretched exponential the so-called Kohlrausch-Williams-Watts (KWW) function, ρ(t) ∝ exp [–(t/τ)^β].