[QE-users] One bug of pw2wannier90 in parallel execution

[박민규]

Dear all users,

Although this might be already known, I want to report my observation in case someone has the same problem but cannot find any hint.

I found that if nband (or nb) option is used in pw2wannier90 step, wannier90 incorrectly gives negative values for Omega_I which is positive quantity by definition. The values also depend on how many cores I used.
I used following command after scf and nscf calculations (you can try to reproduce simply using e.g. example11 of wannier90)
mpirun -n 36 ~/wannier90-3.1.0/wannier90.x -pp wannier
mpirun -n 36 ~/qe-6.5/bin/pw2wannier90.x -nb 3 -nt 3 -in pw2wan.in > pw2wan.out
mpirun -n 36 ~/wannier90-3.1.0/wannier90.x wannier

Someone already reported this negative Omega_I problem long time ago in a different context:
https://lists.quantum-espresso.org/pipermail/wannier/2008-September/000196.html

If I change second one (pw2wannier90.x) to this
mpirun -n 36 ~/qe-6.5/bin/pw2wannier90.x -nt 3 -in pw2wan.in > pw2wan.out
Omega_I has positive value and does not depend on how many cores I used.
Actually nt option does not change the computation time much.

I guess it is good to add an error or warning message like the error message when nk option is used:
Error in routine pw2wannier90 (9):
     pools not implemented

Best regards,
============================================
Minkyu Park
Research Institute of Basic Sciences, University of Ulsan,
Republic of Korea
============================================

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