Thermodynamic Theory of Adam and Gibbs

An alternative thermodynamic theory for the impending entropy crisis based on spin-glass ideas has also been developed in which proximity to an underlying first-order transition is used to explain the glass transition [83]. 

---

It is considered that T2 represents a true thermodynamic transition temperature. A modified transition state theory is developed in which the frequency of molecular jumps relates to the cooperative movement of a group of segments of the chain. The number of segments acting cooperatively is then calculated from statistical thermodynamic considerations. This is the theory of Adam and Gibbs [21], which is described in Section 7.4.3. 

Major open questions where landscape-based ideas should prove helpful include the possible thermodynamic basis for the glass transition (Debenedetti et al., 1999), the relationship between kinetics and thermodynamics of deeply supercooled liquids and glasses (Adam and Gibbs, 1965 Wolynes, 1988), and translation-rotation decoupling and the breakdown of the Stokes-Einstein relationship in supercooled liquids (Fujara et al., 1992). In addition, the reformulation of the thermodynamics of hquids embodied in Eqs. (16), (52), (55), (56), (61), and (62) suggests that understanding basic topological features of a landscape s density-dependent statistics could lead to improved theories of simple and complex liquids. As explained in Section V, landscape statistics can be obtained from experiments, theory, and simulations. 

Resnlts plotted according to the WLF eqnation could be predicted also from the molecular kinetic equation and show that the two approaches are compatible. The Adam-Gibbs equations also lead to a value of (Fg - Fj) = 55 K, so the theory appears to resolve most of the differences between the kinetic and thermodynamic interpretations of the glass transition. 

---