The temperature-dependence of the hopping conductivity of DNA

Abstract Using the matrix block negative factor counting and inverse iteration methods, the electronic density of states (DOS) and wave functions belonging to the energy levels in the valence band regions of an aperiodic DNA base pair stack were determined. From these the hopping frequencies, and with the aid of the latter applying a random walk theory the frequency-dependent complex hopping conductivity of the stack was calculated. The calculations were performed for the frequency range 10 8 s −1 ≤ω≤10 11 s −1 and temperature range 60 K K . According to the results obtained at high frequencies and temperatures, the conductivity indicates variable range hopping (exponential temperature dependence, decrease of the conductivity with decreasing frequencies). The room-temperature conductivity value at high frequency is ∼5×10 −1  Ω −1  cm −1 which agrees well with recent experiments. The experimental and theoretical temperature-dependence at high frequencies also agrees well with each other. At lower frequencies (∼10 8  s −1 ), the conductivity at lower T values doesn't depend on the temperature. This indicates that in the 60 T ω≈10 8 s −1 the dominant mechanism of the conductivity is probably tunneling.