Effects of magnetic field and temperature on the density of states of the poly(dA)-poly(dT) DNA molecule

Charge-transport behavior in poly(dA)-poly(dT) DNA molecules is indicated by the distribution of density of states (DOS) at different electron energies. The DOS of DNA molecules in the presence of magnetic field and temperature is calculated using the tight-binding Hamiltonian and Green's function. The molecule in question consists of 32 base pairs of adenine (A) and thymine (T) in the interior, and a sugar phosphate backbone as the exterior. Electron hopping along the backbone sites is possible with this structure. The DNA molecule is connected to metallic electrodes at both ends. In the model, an external magnetic field modifies the electron-hopping constant through the Peierls transition. Temperature affects the molecule by generating a twisting motion among the base pairs. The results show that temperature and magnetic field limit the DOS of the DNA molecule for a given electron energy. Electrons can occupy all states in the energy spectrum, which are localized states, at temperatures considerably higher than zero.