  Coherent electron transport is investigated in a molecular device made of
polymeric chain sandwiched between two metallic electrodes. Molecular system is
described by a simple Huckel model, while the coupling to the electrodes is
treated through the use of Newns-Anderson chemisorption theory. Transport
characteristics and noise power are calculated in two response regimes: linear
and nonlinear, respectively. Here is shown a strong dependence of the shot
noise on: (i) the length of the polymeric chain and (ii) the strength of the
molecule-to-electrodes coupling. In particular, detailed discussion of
Poissonian to sub-Poissonian crossover in the noise spectra is included.
Presented algorithm allows to calculate the lowest possible level of current
fluctuations (due to Pauli exclusion principle) in designing molecular devices.
