[Wien] new script optimize_abc_lapw

[Peter Blaha]

I think (hope) the parallelization of this script is well described in 
the UG or simply in the "online help" using -h switch. It has multiple 
options and levels for parallelization:

psi11:/psi11/scratch> optimize_abc -h
USAGE: optimize_abc [-h -t 2/3 -sp -p  -n X  -FC X  -d X  -ctest X Y Z 
-ana X  -j "run_lapw -p ..." ]
optimizes a,(b),c lattice parameters
-p      requires the presence of .machines (single jobstep) and
         .machines_1...4 (9) for 4 (9) parallel jobsteps in the 2D (3D) case

The script makes a scf calculation for the present lattice parameter in 
the case directory. This calculation uses the standerd  .machines file 
when specifying "run_lapw -p" as job.

However, then it has to make changes in 4 (or 9 for the 3Dcase) 
directions. This can be done in serial or in parallel (using the -p 
switch of optimize_abc). So with -p it will span 4 (9) run_lapw jobs in 
parallel.
If you still have more cores available, you can in addition supply
.machines_1, .machines_2, ...4 (9) files.

So suppose you have 4 nodes with 16 cores each, you could put into each 
of these .machine_X files 16 different cores (eg. in mpi), but run 4 mpi 
jobs in parallel.
In addition you create a .machines with all 64 cores for the "starting 
job" (at least if it is still efficient for your example. Remember: a 
very small cell will run MUCH LONGER in mpi with 64 cores (or even 
crash) then on fewer cores.

The "task" parallelization is MUCH more efficient then heavy mpi 
parallelization.



Am 15.10.2021 um 17:28 schrieb Mikhail Nestoklon:
> Dear wien2k community,
> I am trying to use new script optimize_abc_lapw on a cluster. Something 
> in its behavior in terms of computer power consumption confused me and I 
> am checking how it actually works. I realized that  at some point (at 
> least when ‘doing x-zchange’) it runs lapw0 and lapw1c and not 
> lapw0_mpi, etc. The most strange part is that when it starts it 
> correctly uses mpi versions of the programs.
> Is this correct behavior?
> I run the script as ‘optimize_abc_lapw -p’ at the end of slurm script 
> which prepares .machines file.
> The structure is hexagonal.
> 
> Thank you in advance.
> Sincerely yours,
> Mikhail Nestoklon
> 
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-- 
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at
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