As a strict minimum, you should write an "unformatted" file, much faster
than a "formatted" one. I don't understand what you are trying to
achieve, though. You can read the QE format with a postprocessing code
(please have a look at pp_example.f90) and do whatever you like with the
Kohn-Sham orbitals, on as many processors you need, without re-writing
everything once again.
Paolo
On 23/11/2022 16:11, Riccardo Piombo uniroma1 via users wrote:
Dear Comunity,
I modified the local_dos.f90 file (see attached file) stored in the
PP/src folder to download the wavefunctions of a system I'm currently
studying.
In particular, I'm running QE on a CINECA supercomputer because my
system contains more than 600 atoms, and I need to run my computations
on several nodes.
My minor modification works well, but I'm facing some problems regarding
the parallelization during the I/O.
For example, If I ask my modified pp.x to write down a single wfc
computed at gamma at fixed band index (say n=1), I obtain a file with
551981 real and imaginary parts of the coefficients of the Plane waves
expansion stored.
However, it takes more than 4 minutes to accomplish this task using just
1 node, and since the default number of bands is 5747, it takes about
22988 minutes = 383 hours = 15 days to download all the wfcs.
Therefore, I decided to run pp.x on multiple nodes. I realized the
number of coefficients saved in the various files is halved every time
the number of nodes is doubled, and the same also happens when the
values of n-tasks-per-node and CPU-per-tasks are not 1 and 48,
respectively (each CINECA node contains 2 CPU with 24 cores each).
Since I don't know how the I/O is parallelized in QE, could someone
suggest how to modify the file so I can use more nodes and avoid that
part of the files is not overwritten?
The only parts of local_dos.f90 that I have modified are the ones
between the following commented lines
/
/
/!##################################################################//
//!!!NEW: print wave functions in G space and corresponding G vectors//
/
/./
/./
/./
/!!!NEW: print wave functions in G space and corresponding G vectors/
/!----------------------------------------------------------------------------------------------------------/
So each modification begins with multiple hashes and ends with numerous
dashes.
My concern is that the WRITE statements I have used are not the right
ones when performing computations over several nodes.
Do I have to open multiple files, one for each node involved?
Best regards,
Riccardo Piombo
Post doc researcher in Condensed Matter Physics at Sapienza University
of Rome
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Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users@lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users
