Coherent electronic charge transport

Landauer proposed in 1957 the first mesoscopic theoretical approach to charge transport [176]. Transport is treated as a scattering problem, ignoring initially all inelastic interactions. Phase coherence is assumed to be preserved within the entire conductor. Transport properties, such as the electrical conductance, are intimately related to the transmission probability for an electron to cross the system. Landauer considered the current as a consequence of the injection of electrons at one end of a sample, and the probability of the electrons reaching the other end. The total conductance is determined by the sum of all current-carrying eigenmodes and their transmission probability, which leads to the Landauer formula of a ID system ... 

It is generally believed that the bases in the centre of the double helix molecule form the pathway for electron transfer. The delocalized p-orbitals in consecutive bases overlap to form a channel for the movement of electrons [7]. The works of Ladik et al. [40] and Bakhshi et al. [41] have led to the assumption that the transmission channels are along the long axis of the DNA molecule [101, 107-109]. Several mechanisms have been given for charge transport in DNA, but the dominant ones are the coherent transport via extended molecular orbitals, and the thermal hopping mechanism. 

The charge transport in organic crystals is conventionally described either as a coherent or an incoherent process with respect to the interaction strength of the charge carrier with lattice vibration. In the weak electron phonon interaction... 

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