Fig. 3.
Temperature dependence of time autocorrelation function of local tetrahedral order parameter and relaxation times. (A) Autocorrelation function C Q(t) of tetrahedral order parameter Q at various temperatures. C Q(t) is exponential at high temperatures but displays a visible two-step decay at low temperatures. (B) Correlation time τQ extracted from C Q(t) (circles). The solid line is the fit using the Adam–Gibbs relation (Eq. 13) between the tetrahedral entropy S Q(T), and the tetrahedral relaxation time τQ. The dotted lines in B show the power-law fit B(T − T MCT)−γ with the fitting parameters B = 25.39, T MCT = 246.18, and γ = 1.17. The behavior of τQ deviates from the power-law fit for the temperatures below the Widom-line temperature (indicated by a vertical arrow) T W where a cross-over to Arrhenius behavior at lower temperature occurs.