[Q-e-developers] A few questions about implementing qe post-processing

[Ye Luo]

Hi QE developers,

I'm working on improving the interface program pw2qmcpack and I've a few
questions.

Usually we do scf->nscf->pw2qmcpack to get the final WF file. I need qe
expert to help me understanding better the pw.x behavior.
Assuming wf_collect=.false.
I mean "parallel setup" by procs and k-pools. Only 1 image is used.

1, It is not required to run the nscf with the same parallel setup as the
scf run. I tried, it seems working well. nscf doesn't need WF but density,
right?
2, If I use a complete different list of k points and use different
parallel setup for the nscf. The WF stored in "*.wfc?" in the out
directory  will be the one correspond to nscf run because the WF of scf run
is overwritten by nscf run. It seems so, but please confirm.
3, The following pw2qmcpack run needs to load the WF from the last nscf
run. I'd like to add gatekeeping code to check whether the converter is run
with the same parallel setup as the last nscf run. I tried checking
nproc_pool_file as the postproc.f90. It seems that this variable keeps the
original value from scf run rather than nscf run. So is there a way to
access the last nscf paralle setup?
4, I noticed that when I tried to write(*,*) from the first MPI task
associated to a pool. I got the contents on Intel build but not on BG/Q. It
is not critical but introduce difficulty to print out some debug info. I
feel strange that the same code show different behaviors. If you know the
reason, please explain it.

Thanks a lot!

Ye

===================
Ye Luo, Ph.D.
Leadership Computing Facility
Argonne National Laboratory
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