Relaxation time distribution function

The distribution function of relaxation time in disordered dielectrics has been calculated in the random field theory framework. For this purpose, we first consider the dynamics of single two-orientable electric dipole in a r andom electric field E in a disordered ferroelectric. The obtained dependen ce tau(E) made it possible to express the relaxation time distribution func tion F(tau) via the random field distribution function f(E). This function has been calculated self-consistently in the random field theory framework. Nonlinear random field contribution and effects of spatial correlations be tween the dipoles have also been taken into account. It was shown that nonl inear contribution of random field gives asymmetric shape of F(tau) while i n linear case it is symmetric. Comparison of calculated F(tau) curves with those extracted from empirical Cole-Cole (CC), Davidson-Cole (DC), Kohlrausch-William-Watts (KWW) and Havr iliak-Negami (HN) functions had shown, that they correspond to mixed ferroe lectric-dipole glass (ferro-glass) phase with coexistence of shea and long- range order. Different forms of F(tau) are determined by linear (CC) or non linear (DC, KWW, HN) contributions of random field.