Thermal Vibration and Twist Induced Semiconducting Behaviour in Short DNA Wires

We study the transport properties of electrons in a short homogeneous DNA molecule where thermal vibrations and twist fluctuations of the base molecules are considered. The nonlinear current-voltage curves can be derived by using the equivalent single-particle multichannel network. The voltage gap is sensitive to the strength of thermal vibrations and twist fluctuations of the base molecules. Our results are in good agreement with the recent finding of semiconducting behaviour in short poly(G)-poly(C) DNA oligomers. The present method can also be used to calculate the other molecular wires