  Hierarchically nanostructured materials, where disorder is introduced in
various length scales (at the atomic scale, the nanoscale, and the mesoscale)
is one of the most promising directions to achieve extremely low thermal
conductivities and improve thermoelectric performance. Here we theoretically
investigate one such system, a nanocrystalline material with nanopores that are
introduced between the crystalline regions. We use the Nonequilibrium Greens
Function method for electronic transport and Molecular Dynamics for phonon
transport.
