and the black-dashed for AOP. ](Figure_2.png "fig:"){width="8.6cm" height="14.2cm"}\

It turns out that a lot about the thermoelectric transport can be understood by looking at the energy of the current flow, $\langle E(x) \rangle$, along the transport direction, as defined in Eq. (\[eq14\]). This states, as expected, that the higher in energy the current flows with respect to the Fermi level, the higher the Seebeck coefficient is. It also provides some indication about the electrical conductivity, i.e. the higher the energy of the current flow, the more electrons with higher velocities are utilized (assuming no complex bandstructure effects cause velocity reductions), and the higher the conductivity could be. As we will show below, it proves to be a very useful feature in understanding TE transport particularly in the nanostructured materials we consider, and below we describe how we use it to interpret our simulation results.

Figure 2 shows $\langle E ( x ) \rangle$ for different structure cases and scattering conditions. Figure 2(a) considers a channel with two SL-type barriers inserted (black SL barrier lines). The colormap in all subfigures shows the energy and spatial regions where the current flows (yellow) in the case where both acoustic and optical phonon (AOP) 