[QE-users] Assistance with Phonon Dispersion Calculation for Au

[Md. Jahid Hasan Sagor]

Hi,

I am currently working on plotting the phonon dispersion for gold (Au).
When using a unit cell with a single atom, I was able to generate the
dispersion easily by following the steps: pw.x, ph.x, q2r.x, and matdyn.x.
However, when I used a 3x3x3 supercell containing 27 atoms, the calculation
became significantly slower during the ph.x step. Additionally, I cannot
take advantage of symmetry to simplify the calculations because the atomic
positions I am using are temperature-dependent and not in equilibrium,
meaning the symmetry conditions are not obeyed.

To provide some context, I ran the ph.x calculation on 2 nodes with 32 CPUs
each (a total of 64 processors). Despite this setup, the computation time
is still extremely long. I am sharing the input and output details of my
calculations and would greatly appreciate any advice or suggestions on how
to optimize and accelerate the process.

pw.x (input)

[image: image.png]

ph.x (input)
[image: image.png]

HPC setup:
*nodes=2*
*ntaskes-per-node=32*
*cpus-per-task=1*
*mem-per-cpu=20gb*
*time=360:00:00*



And ph.out is attached herewith.

Thank you

Best Regards
Md Jahid Hasan Sagor
PhD student, Mechanical Engineering
University of Maine
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