[Pw_forum] phonon errors (vtmtrinh at caltech.edu)

[vtmtrinh at caltech.edu]

Dear Miguel and Mikiyas,

Thanks for your help.

Yes, I am sure that the outdirs are in the same directory. My main purpose
is to calculate the phonon dispersion curve from Gamma to X for Si. I'd
like to reproduce the Si phonon dispersion curve from Gamma to X.  I
thought that after the scf calculation for 10x10x10, I can run phonon
calculation directly for a series of q points from Gamma to X (let say 5
points).  Then from there, I use q2r.x and then dynmat.x to calculate
intermediate points in order to fix the non-zero frequency at Gamma point
(applying ASR) and to get a smooth dispersion curve curve.  However, the
phonon calculation (the first crash) crashed all the times.  Now I am
testing by running phonon calculation for a mesh of 4x4x4 to see if it
still crashes. If it works, this means that direct calculation of phonon
by specifying directly q points along G-X does not work.  However, this
will be expensive calculation if to get phonon dispersion a long one
direction, I have to do the 3D-messh phonon calculation first.

If I did only a single q-point calculation one at a time, which would be
much faster than does the approach above, how could I specify q-grid in
q2r.x?

Also, I have another question, if I would like to apply ASR to fix the
phonon freq. at Gamma point, is it correct to just specify the q-grid in
the input files for q2r.x and matdyn.x as follows:

&input
    fildyn='si.dyn', zasr='crystal', flfrc='si.fc'
  /
 1 1 1
 1
 si.dyn1    !this the *.dyn file at gamma

Best,

MyTrinh



>
> On Oct 7, 2009, at 3:24 AM, pw_forum-request at pwscf.org wrote:
>
>>
>> Message: 7
>> Date: Wed, 7 Oct 2009 00:07:18 -0700 (PDT)
>> From: vtmtrinh at caltech.edu
>> Subject: [Pw_forum] phonon errors
>> To: pw_forum at pwscf.org
>> Message-ID:
>> 	<2940.137.78.73.28.1254899238.squirrel at webmail.caltech.edu>
>> Content-Type: text/plain;charset=iso-8859-1
>>
>> Dear PWSCF Users,
>>
>> I have 2 questions:
>>
>> 1. I did a test phonon calculation for Si bulk, 2atom-cell, following
>> example_06.  I first did an scf calculation with k-point mesh
>> 10x10x10 Si.
>> Next, I wanted to do a phonon calculation along [001] direction (i.e
>> q=0,
>> q=0.1, 0.2,...).  If I specified 'ldisp=.true.', it was supposed to do
>> nscf calculation and then phonon calculation in a series.  However, it
>> stopped with errors.  When I checked the output file, after it had
>> finished calculation at Gamma point and nscf calculations, when it
>> entered
>> the phonon calculations for q !=0, it stopped with the error:
>>     task #         8
>>     from openfilq : error #         1
>>     file si.wfc not found
>> The run is supposed to run continously as I specified ldisp=.true.
>> Now
>> suddenly, it stopped with that error, so I could not understand
>> why.  When
>> I tried with different q-point mesh, e.g. 4x4x4.  I ahd the same
>> problem.
>>
>> Here is my input for the phonon calculation:
>>
>> phonons of Si bulk
>> &inputph
>>  tr2_ph=1.0d-14,
>>  prefix='si',
>>  ldisp=.true.,
>>  nq1=1, nq2=1, nq3=10   !(or nq1=4, nq2=4, nq3=4 for second test)
>>  amass(1)=28.086,
>>  outdir='./',
>>  fildyn='si.dyn',
>> /
>>
>> 2. If I run each single q-point,i.e. did scf, then Gamma
>> calculation, then
>> nscf and phonon calculation for each single q-point, it was fine. I
>> obtained 6 dyn files for 6 q-points from 0 to 0.5. However, I had
>> problem
>> when I used q2r.x.  In the input file, q2r.in, if I specified the q-
>> point
>> mesh: 1 1 10, and below it I provided a list of 6 dyn files that I
>> calculated above, I got an error:
>>
>>  task #         0
>>     from init : error #         1
>>     q not allowed
>>
>> I am not sure what is the correct input for the q-point mesh in q2r.in
>> that I should use in this case.
>>
>> Below is my q2r.in:
>>
>> &input
>>   fildyn='si.dyn', zasr='crystal', flfrc='si.fc'
>> /
>> 1 1 10
>> 6
>> si.dyn1
>> si.dyn2
>> si.dyn3
>> si.dyn4
>> si.dyn5
>> si.dyn5
>>
>> I am using QE version 4.0.3.
>>
>> Thank you very much,
>>
>> MyTrinh
>> JPL/CakTech
>>
>>
>>
>
> Dear,
>
> It is essentially complaining that the data from your first pw.x run
> is not found in the outdir under that prefix ("si"). Have you checked
> that the outdir matches in both input files? Also, you can manually
> make sure that Si.wfc does exist in the outdir. Another helpful thing
> to do is to clear the outdir before you do these runs.
>
> - Mikiyas Tsegaye
> University of Virginia
> Charlottesville, VA, USA
> mastermik at gmail.com
>
>
>
>
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