Hello Giovanni,
thank you very much for the quick reply and the tips. As requested, here
is my execution line:
export OMP_NUM_THREADS=48.
mpirun -np 10 pw.x -in input/“$INPUT” -nb 1 -nt 2 > output/"$OUTPUT”
I'm trying to run MPI+openMP in a hybrid way, since using pure MPI has
prohibitively increased the use of RAM. Regarding the second point, I
used K_POINTS gamma for the supercell calculations, I don't know if
that's exactly your question. As for ecutwfc and ecutrho, I used 50 Ry
and 400 Ry respectively. Regarding the fourth point, as these are steps
in a finite displacement process, at least one coordinate will be subtly
disturbed, referring to the displacement of the atom of the method
itself, but in fact as you mentioned, there were other coordinates that
were a little disturbed due to the relaxation I did with vc-relax before
generating the supercell, which changed the atomic positions a little
for these strange coordinates. I'm already testing the calculation
without this relaxation to see if it improves. I'm still looking for
more suggestions to improve the calculation.
Sincerely,
M.Sc. Mateus Corradini Lopes
PhD. student
Gleb Wataghin Institute of Physics - Unicamp
Em 22/05/2025 16:34, Giovanni Cantele escreveu:
Hi,
first of all it would be nice also to have the command you use to run
pw.x (because if you for example use pools, this replicates the memory
requirements).
Second: which k-point grid do you use to sample the Brillouin zone? In
the case of a 1x1x1 grid, do you use gamma-only algorithms?
Third: which ecutwfc and ecutrho do you use?
Fourth: I understand you need a "perfect" supercell as derived from
replicating a bulk cubic cell. Coordinates like 0.0013807042891237
or 0.1874999906250000 are harmful (unless you need to break symmetry
or they are exactly what you want), in that they prevent pw.x from
finding symmetries. The latter might be quite helpful in (sometimes
even significantly) reducing the calculation load (in terms of
k-points but not only!). So, I would round all coordinates so as to
obtain exactly the number you expect.
Hope this helps.
Giovanni
--
Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cant...@spin.cnr.it <mailto:giovanni.cant...@spin.cnr.it>
Phone: +39 081 676910
Skype contact: giocan74
ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home
Il giorno gio 22 mag 2025 alle ore 20:03 Mateus Corradini Lopes
<mclo...@ifi.unicamp.br> ha scritto:
Dear all,
I have recently been working on obtaining transport properties for
certain types of materials. One of the parts of the work is to obtain
the lattice thermal conductivity (\kappa_latt), so I'm trying to use
phono3py+Quantum Espresso to calculate the supercell and obtain the
force constants.
At the moment I'm trying to calculate the \kappa_latt of GaAs as a
test,
I've already managed to generate the supercells (4x4x4 and 3x3x3
based
on the conventional GaAs cell, which gives 512 and 216 atoms
respectively) and I've used phono3py's --cutoff-pair to reduce the
number of inputs, but even though I've tried various ways of
running the
calculation I haven't found a way to make it feasible in terms of
computational time and RAM (the lowest I could get was “Estimated
total
dynamical RAM > 115.43 GB”). I have access to a cluster with 480
processors (10 nodes with 48 processors each) and I would like to
know
what is the best way to run this system, in terms of optimizing the
input and the parallelism used, balancing precision and
computational time.
Ps. I'm attaching an example of the input I'm currently using.
Thank you in advance,
M.Sc. Mateus Corradini Lopes
PhD. student
Gleb Wataghin Institute of Physics - Unicamp
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_______________________________________________________________________________
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worldwide who are victims of terrorism, military aggression, and indiscriminate
warfare.
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