Langevin loops

Fig. 4.22. Comparison between NMF as measured by FCS [46] and simulation using Langevin description [67] with a 2-loop cycle...

The periodicity in the NMF indicates the presence of non-equlibrium processes with periodic solutions and is related to the number of states and the transition rates [46, 67]. It is important to mention that the Langevin simulations are very sensitive to the model used and the identity with the experimental data set is indicative for a driven conformational loop which is coupled to the catalytic step generating the substrate product conversion with photon emission (Fig. 4.22). 

Compared with simulations of the two state model we find perfect agreement. Fitting the time T on the excitation loop as well as the two excitation rates tq and ri to the FHN system, also leads to a reasonable agreement between theory and Langevin simulations of the FHN system. 

The dependence of mean polarization (P3) on the applied electric field in shown in Fig. 4.38a for uniaxial material (Rochelle Salt) parameters, Dirac-delta distribution [T(7 ) = 8(7 — Rq) of particle sizes, fixed freezing radius Rf(T) at temperature 7 = 0 °C and different average nanoparticle radii Rq. Curves 1 for Rq < Rf correspond to Langevin law, while curves 5-7 for Rq > Rf indicate the hysteresis loop appearance. 

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