Yes, the tutorial assumes doping and more specifically it computes the impurity-scattering limited mobility. If you are interested in the phonon-limited mobility, which is what matters in an intrinsic, undoped material, obviously you need to include phonons in your calculation, which is not so trivial (but will be possible in ATK 2015).
Although experimentally there is of course one specific mobility for a material, it's actually a rather tricky quantity to calculate. You can try to include all possible scattering mechanisms, and then the calculation is typically done using a Monte Carlo simulation, but it requires that you know all scattering rates. These can be computed from first principles (again, will be possible in ATK 2015) but often need to be calibrated against experiments. Or, you can try to pick a specific scattering mechanism "x" and compute the x-limited mobility . But the approach in these cases can be quite specific for the mechanism - you couldn't use the approach in our tutorial for phonons, since you need to account for vibrations, but these can on the other hand be captured in an MD simulation, as presented in
T. Markussen's presentation at our conference QuantumHagen 2014 (the slides are available on the abstract page).
