In addition to the silicon example discussed above, we provide several tutorial examples to explore the various capabilities of Perturbo. Before starting this tutorial, please read the sections on qe2pert.x and perturbo.x of this manual.

For each example in the tutorial, we use three directories to organize the results of the calculations:

• pw-ph-wan: contains files for the scf, nscf, phonon, and Wannier90 calculations when running Quantum Espresso (QE)

• qe2pert: contains files for running qe2pert.x to generate an essentail file ‘prefix’_epwan.h5 for perturbo calculations

• perturbo: contains files for running perturbo.x

As a reminder, here are the steps needed to compute prefix_epwan.h5:

• Step 1: scf calculation
• Step 2: phonon calculation
• collect all the data into a directory called “save”
• Step 3: nscf calculation
• Step 4: Wannierization with Wannier90
• Step 5: run qe2pert.x
• soft link ‘prefix’_centres.xyz, ‘prefix’_u.mat (and, when present, ‘prefix’_u_dis.mat) in the directory “pw-ph-wann/wann”
• create a directory called “tmp”, and inside it soft link the QE nscf output directory ‘prefix’.save in the “pw-ph-wann/nscf/tmp”