Current fluctuations of polymeric chains

Coherent electron transport is investigated in a molecular device made of a polymeric chain sandwiched between two metallic electrodes. The molecular system is described by a simple Huckel model, while the coupling to the electrodes is treated in a broad energy band approach. Transport characteristics and noise power are calculated in two response regimes: linear and non-linear. A strong dependence is shown of the shot noise on (i) the length of the polymeric chain and (ii) the strength of the molecule-to-electrode coupling. In particular, a detailed discussion of Poissonian to sub-Poissonian crossover in the noise spectra is included. An algorithm is presented that allows one to calculate the lowest possible level of current fluctuations (due to the Pauli exclusion principle) in designing molecular devices. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.