The transmissions as functions of energy are central for electron or phonon transport in the Landauer transport picture. We suggest a simple and computationally "cheap" post-processing scheme to interpolate transmission functions over $k$-points to get smooth well-converged average transmission functions. This is relevant for data obtained using typical "expensive" first principles calculations where the leads/electrodes are described by periodic boundary conditions. We show examples of transport in graphene structures where a speed-up of an order of magnitude is easily obtained.
Falkenberg, J. T., & Brandbyge, M. (2015). Simple and efficient way of speeding up transmission calculations with k-point sampling. Beilstein Journal of Nanotechnology, 6(1), 1603–1608. https://doi.org/10.3762/bjnano.6.164