The transport properties of poly(G)-poly(C) DNA oligomers in the Harrison's model

Using the tight-binding Hamiltonian of the Harrison's model and the Landauer-Büttiker formalism, some of the electron transport properties of short poly(G)-poly(C) DNA segments lying between two semi-infinite carbon chains as the nanoleads are investigated. The analytical results of the self-energies due to the leads are represented by solving the discretized form of the one-dimensional Schrödinger's equation. Under the Harrison's model, with considering in-phase overlap between the nearest neighbors' all kinds of atomic orbitals, the influences of more atomic orbitals in central channel and backbone of DNA (according to Fishbone model) on the electron transmission probability are discussed. Transmission probabilities for both the single- and many-orbital states are calculated and compared with each other. Furthermore, the effect of increasing length of the DNA nanowire and the coupling strength of nanolead/DNA interface on transmission probability and the current-voltage (I-V) curves and also the effect of different temperatures of the leads on the I-V characteristics are studied. Our results show that the poly(G)-poly(C) DNA oligomer exhibits a semiconducting behavior and that the vertical coupling strength between base pairs and the sugar-phosphate backbone in poly(G)-poly(C) DNA structure can induce the semiconducting gap.