Super-Arrhenius behavior

Inherent structure analysis of diffusion via molecular dynamics of a deeply supercooled binary Lennard-Jones fluid have provided renewed impetus to the decisive role played by thermodynamic factors [52,53]. The location of the mode crossover temperature and the onset of super-Arrhenius behavior were related to the static structure of the liquid via the potential energy hypersurface [52,53],... 

The reversible step may be related to the dynamic crossover in protein hydration water at To 345 5K. NMR self-diffusion results [19] indicate that at this temperature a sudden change in hydration water dynamics occurs and the inverse diffusion constant switches from low-temperature super-Arrhenius behavior to high-temperature Arrhenius behavior. Neutron techniques (QENS) have also been used to study protein hydration water at this high-r crossover. Figure 21 shows the atomic MSD of protein hydration water at the low-r crossover measured using MD simulation. These crossovers can also be shown theoretically. Whenever the slope of an Arrhenius plot of the D T) changes, the specific heat has a peak. The well-known Adam-Gibbs equation (AGE) shows this as... 

Fig. 3. Temperature dependence of structural relaxation time t (Jeong et al., 2010). Lines are the fitted results using (a) r = ci exp(di/T ) and (b) t = C2 exp(d2/T). A super-Arrhenius behavior shown in (a) and (b) suggest that our model of RULs resembles a fragile glass former.

Figure 2.4, on the other hand, shows behavior for some inorganic ILs [20] which, while superficially similar to that of Figure 2.3 (super-Arrhenius), is almost... 

Figure 11 shows a typical example of the temperature-dependent behavior for the reactions of OH radical with aromatic compounds. The measured bimolecular rate constants of OH radical with nitrobenzene showed distinctly non-Arrhenius behavior below 350°C, but increased in the slightly subcritical and supercritical region. Feng a succeeded in modeling these data with a three-step reaction mechanism originally proposed by Ashton et while Ghandi etal. claimed to have developed a so-called multiple collisions model to predict the rates for the reactions of OH radical in sub- and super-critical water. 

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