Linear response theory breakdown

The problem of the breakdown of linear response theory could be approached in a somewhat different way. Let us consider the case where ( of Eq. (5.43) is veiy close to (v )eq- This means that... 

A published derivation of the Green-Kubo or fluctuation-dissipation expressions from the combination of the FR and the central limit theorem (CLT) was finally presented in 2005. This issue had been addressed previously and the main arguments presented, but subtleties in taking limits in time and field that lead to breakdown of linear response theory at large fields, despite the fact that both the FR and CLT apply, " were not fully resolved. ... 

The condition for the breakdown of linear response theory, Eq. (47), now reads... 

Movaghar et al.(56) have shown that this distribution function for the event times leads to a breakdown of the linear response theory in the long time domain, which means that drift current and electric field are no longer linearly related. Instead... 

It is somewhat surprising in the light of this evidence that attempts to observe carrier transit have been unsuccessful [100 -102), After a short light pulse the photocurrent decays monoton-ically with no features attributable to carrier transit. Such a response, of the form t °, is in fact typical for amorphous materials an apparent paradox in view of the quality of the PDA crystals used. This problem has been resolved by recent theoretical and experimental work [103, 104). These show that the apparent anomaly is due to a breakdown in linear response theory. Carrier motion in ID in the presence of strong scattering centres is shown to be extremely sensitive to the density of scattering centres. 

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