Scaling properties of dynamic response in orientational glasses

The freezing transition in dipolar and quadrupolar glasses is characterized by the presence of local random electric and strain fields generated by su bstitutional disorder. The dynamic response in the ergodic phase above the freezing temperature T-f is studied in terms of Langevin dynamics applied t o the recently formulated symmetry-adapted random-bond-random-field (SARBRF ) model of orientational glasses. Following the theory of spin glasses it i s assumed that for T greater than or equal to T-f the response can be writt en in a dynamic scaling form by introducing a scaling exponent v and a freq uency scaling variable. The value of v(T) is explicitly evaluated for the q uadrupolar (100) SARBRF model, and its relation to the experimentally obser ved effective exponent v(eff)(T) in dipolar and quadrupolar glasses is disc ussed.