Non-Equilibrium Processes in Amorphous Solids

For a temperature or pressure jump, the rate of the structural relaxation is expressed in terms of a characteristic relaxation time t. As a working approximation, the rate of approach of the density and configuration to their equilibrium values can be treated as first-order kinetic processes. Thus, the change in enthalpy accompanying the relaxation is expressed by 

A more refined and realistic treatment takes account of multiple, partly superimposed relaxation processes (stretched relaxation) by including a distribution parameter P in the relaxation function, where 0 p 1  

A second approximation stipulates that the temperature dependence of t follows Arrhenius kinetics, so that 

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