Structural signature of super-Arrhenian behavior

In this communication we report on a promising candidate for a structural feature that correlates with the emergence of super-Arrhenian behavior in glass forming materials. MD simulation were carried out for a binary mixture of 80% AB and 20% CD dumbbells for a wide temperature range encompassing liquid and super-cooled liquid state, where the interaction potentials and particle diameters of the dumbbells are chosen to suppress crystallization. The relaxation time is evaluated via rotational and translational diffusion, where the relaxation time exhibits Arrhenian temperature dependence above T_A and super-Arrhenian dependence below T_A. The full orientational correlator F₀ for the long axes of the AB dumbbells was calculated, where the correlator has a value of unity if orientations of the molecules are perfectly random. At high temperatures above T_A F₀=1; however, at T_A the correlator F₀ departs from unity.