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Low-Temperature ac Conductivity of disordered non-metals
Internt fagligt projekt, 3.. modul, 2001, id:175
Vejleder:Jeppe C. Dyre
Findes på RUb:ja
English abstract
The random site no barrier (RSNB) hopping model consists of random site energies and Miller-Abrahams transition rates. Particle interactions are disregarded and jumps are only nearest neighboyr. At low temperatures the model can equally well describe ion- and electron transport. The RSNB model is investigated in the one-dimensional case. The model is only solvable through approximative methods. First the analytic effective medium approximation (EMA) is trested. Various asymmetric EMA mothods are analyzed, among them tho only one at the present time that incorporates the RSNB model as its main target. I extend this method to the low-temperature limit, where the result equals that of low-temperature limit random barrier EMA. This is the expected result, since the effective charge transport of the RSNB model at low-temperatures is expected to consist of transport between few low-energy sites, and movement between these sites resembles over-barrier jumps with spatial disorder. According to computer simulations on a N = 1024 lattice, the RSNB model with box distributed site energies converges towards a single curve in the low-temperature limit. The curve is compared to the EMA low-temperature prediction, which resembles that of low-temperature random barrier EMA. The result is not nearly as close to EMA as seen for random barrier simulations.

Database opslag den: 25-01-2021