Why do we need to run self-consistent calculation twice?

[vladgladkikh]

I am new to EPW, reading the tutorials, and what I noticed is that self-consistent calculations are run twice:

1) Before calculating phonons in the phonons directory

2) After calculating phonons in the epw directory, to which we copy files calculated in the phonons directory using pp.py

Why should we run self-consistent calculations twice? Why not calculate everything in the same directory?

[sponce]

Hello,

We like to decouple things so that everything is clear.
In principle it is indeed not needed and the following should work
scf.in
ph.in
pp.py
nscf.in
epw.in

Best wishes,
Samuel

[vladgladkikh]

Dear Samuel,

Thanks for your reply!

Best regards,

Vlad