It is also possible to approach electronic transport problems from an atomistic viewpoint, most notably by means of ab initio density functional TAK960 calculations (DFT) coupled with non-equilibrium Green function methods [4] and [26]. However, the computational cost of these calculations can be considerably high. Moreover, all current DFT implementations require at least some degree of periodicity in order to handle large systems (≈103 atoms), which unfortunately is clearly not present in disordered CNT networks. Nonetheless, ab initio methods have been used to investigate electrical resistance at single wall nanotube (SWNT) junctions [34], and more recent studies have extended these results considering the presence of O2O2 and N2N2 molecules [21] near the junction. The use of first principles methods for obtaining the quantum conductance between individual nanotubes is able to shed some light on the quality of the junction, but collenchyma is unable to reproduce the general observed features in network films because it is not capable of including disorder effects to the scale required. The alternative of carrying out a fully atomistic transport calculation within a heavily disordered environment is very desirable but it is currently too computationally demanding. It is therefore necessary to compromise if one wishes to combine the two features.
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