Run the preliminary calculations (scf, phonon, nscf, and Wannier90) in the directory “pw-ph-wann”. The input file for a 2D material for qe2pert.x requires to an extra variable, system_2d = .true. Here is the input file:

&qe2pert
prefix='graphene'
outdir='./tmp'
phdir='../pw-ph-wann/phonon/References/save'
nk1=36, nk2=36, nk3=1
dft_band_min = 1
dft_band_max = 11
num_wann = 2
lwannier = .true.
system_2d = .true.
/


In the input files for perturbo.x, the user does not need to specify any variable related to 2D systems, since perturbo.x will know from the ‘prefix”_epwan.h5. When running the calculation modes 'setup' or 'trans', the carrier concentration units are cm-2 instead of cm-3. In this example, we focus only on the two bands that cross the Dirac cone of graphene. The band index is 1 for the valence and 2 for the conduction band. In the electron mobility calculation, we set accordingly both band_min and band_max to 2. In the hole mobility calculation, both band_min and band_max are set to 1.