Conduction Kivelson Model

In the case of weakly FeCla doped PPPs, the dc conductivity (Cdc) was proportional to T n 10). This result, which is very different from Mott s relationship, was interpreted as being due to hopping and fitted a relationship involving a slightly modified Kivelson model [228] between polarons and bipolar-ons. With more heavily doped PPPs, the charge transport mechanism changed dramatically, and Cdc was then given by Mott s relationship corre-... 

The dimensional structure of these materials. If we consider that there is no reticulation, these materials can appear one-dimensional in relation to both charge transfer and vibrational energy. This apparent anisotropy should be considered only local (at a short distance) because the study of conduction phenomena shows an isotropy of transport properties, which is quite well explained with the theory of interchain hopping mechanisms (Kivelson model [22] for solitons polaron lattice introduced by Bredas and coworkers [23,24]). 1 will show that the heterogeneous polymers model may also be used. 

The soliton conductivity model for rrans-(CH) was put forward by Kivelson [115]. It was shown that at low temperature phonon assisted electron hopping between soliton-bound states may be the dominant conduction process in a lightly doped one - dimensional Peierls system such as polyacetylene. The presence of disorder, as represented by a spatially random distribution of charged dopant molecules causes the hopping conduction pathway to be essentially three dimensional. At the photoexitation stage, mainly neutral solitons have to be formed. These solitons maintain the soliton bands. The transport processes have to be hopping ones with a highly expressed dispersive... 

Similar to Kivelson s model. Chance and co-workers proposed interchain hopping for spinless conductivity in doped polyacetylene, doped poly(p-phenylene) and other doped polymers [102]. The mechanism accounts for the observed dopant concentration dependence of the conductivity in rans-polyacetylene and the observation of anomalously... 

Moses et al. [98] have measured the conductivity of tra/is -polyacetylene at various pressures. In Kivelson s model at all pressures there should be the same temperature dependence [85]. In the case of variable-range hopping, however, the temperature dependence should change with pressure, because the density of states at the Fermi level changes [97]. The experiment shows no difference in the temperature dependence between ambient pressure and 8.74 kbar. Moses et al. [98] take this as an evidence for the Kivelson mechanism. 

Figure 6 exhibits the conductivity due to intra- and interchain soliton diffusion in slightly iodine-doped trans-PA. The intrachain charge transfer was analyzed in terms of phonon-assisted spin hopping between soliton sites, in the framework of the Kivelson phenomenological model, with predicted conductivity... 

Figure 6 also shows the contribution of both ID and 3D polaron motions to the ac conductivity of the laser-modified PATAC. Its intrachain conductivity Oid was interpreted in terms of the model of the charge-carrier scattering on the lattice optical phonons proposed by Kivelson and Heeger for metal-Uke clusters in conjugated polymers, ... 

S. Kivelson, Electron hopping conduction in the soli-ton model of polyacetylene, Phys. Rev. Lett. 46(20) 1344 (1981). 

A model found to correctly predict the steep increase in conductivity of P(Ac) on doping and dependence of P(Ac) on temperature is that proposed by Kivelson [180, 181]. In its essence, this "intersoliton hopping" model applied primarily to P(Ac) proposes isoenergetic hopping of electrons from a neutral soliton of one chain to a charged soliton at a neighboring chain via tunnelling. It is able to account well for... 

Delineate the salient points of each of the following conduction models Mott VRH Sheng Paasch Kivelson electronic. Identify which temperature and doping ranges each model is most correctly applicable to. 

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