EPW Forum

Posted: **Tue Oct 04, 2022 12:52 pm**

Dear all,

I am using QE to calculate phonon dispersion of copper. But I found my result is different with reference. Could you find some problems in my calculation?

Code: Select all

&CONTROL
  calculation='scf'
  pseudo_dir='./'
  outdir='./'
  restart_mode='from_scratch' 
  prefix='Cu'
/
&SYSTEM
  ibrav= 2 
  nat= 1
  ntyp= 1 
  celldm(1)=6.834030 
  ecutwfc = 90
  occupations='smearing'
  degauss=0.01
/
&ELECTRONS
  conv_thr = 1.0d-10
/
ATOMIC_SPECIES
  Cu 63.546 Cu_pbe_v1.2.uspp.F.UPF
ATOMIC_POSITIONS (crystal)
  Cu  0.0000000000  0.0000000000  0.0000000000
K_POINTS {automatic}
  11 11 11 1 1 1

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phonon calculation
&inputph
  outdir='./'
  prefix='Cu'
  tr2_ph=1.0d-14
  ldisp=.true.
  amass(1)=63.546 
  nq1=4,nq2=4,nq3=4
  fildyn='Cu.dyn'
  fildvscf='dvscf'
/

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&input
  fildyn='Cu.dyn'
  zasr='simple'
  flfrc='Cu.fc'
/

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&input
  asr='simple'
  amass(1)=63.546
  flfrc='Cu.fc'
  flfrq='Cu.freq'
  q_in_band_form=.true.
  q_in_cryst_coord=.true.
/
6
0.0000 0.0000 0.0000 30
0.0000 0.5000 0.5000 30
0.2500 0.5000 0.7500 30
0.0000 0.5000 0.5000 30
0.0000 0.0000 0.0000 30
0.5000 0.5000 0.5000 30

The figure at the bottom is my result.

: 2.jpg (91.41 KiB) Viewed 7525 times

Posted: **Wed Oct 05, 2022 4:49 pm**

Dear wqx:

Basically, the question on the phonon code in QE should be asked on the QE forum.

In any case, I think the issue with your inputs is related to your chosen path; for instance, the coordinate of the 2nd (1st) point is different from that of the 4th (5th) point.

Code: Select all

6
0.0000 0.0000 0.0000 30
0.0000 0.5000 0.5000 30
0.2500 0.5000 0.7500 30
0.0000 0.5000 0.5000 30
0.0000 0.0000 0.0000 30
0.5000 0.5000 0.5000 30

You can confirm it by comparing the distance between the 1st and the 2nd point with that between the 4th and the 5th point in your reference figure.

Sincerely,

H. Lee

Posted: **Thu Oct 06, 2022 3:04 am**

hlee wrote: ↑Wed Oct 05, 2022 4:49 pm Dear wqx:

Basically, the question on the phonon code in QE should be asked on the QE forum.

In any case, I think the issue with your inputs is related to your chosen path; for instance, the coordinate of the 2nd (1st) point is different from that of the 4th (5th) point.
Code: Select all
6
0.0000 0.0000 0.0000 30
0.0000 0.5000 0.5000 30
0.2500 0.5000 0.7500 30
0.0000 0.5000 0.5000 30
0.0000 0.0000 0.0000 30
0.5000 0.5000 0.5000 30
You can confirm it by comparing the distance between the 1st and the 2nd point with that between the 4th and the 5th point in your reference figure.

Sincerely,

H. Lee

Dear H. Lee,

Thank you for your help! I checked my reference and my codes. K path is the key issue of phonon dispersion.

Best wishes.

wqx

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phonon dispersion of copper

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