[QE-developers] Fwd: Different output information in phonon calculation of 'GRID' and'SPLIT'

[Paolo Giannozzi]

---------- Forwarded message ----------
From: 黄志硕 <zhishuohuang at gmail.com>
Date: Wed, Mar 28, 2018 at 2:40 PM
Subject: RE: Different output information in phonon calculation of 'GRID'
and'SPLIT'
To: Paolo Giannozzi <p.giannozzi at gmail.com>


Dear Prof. Paolo Giannozzi,



Thank you all the same for your response.



By the way, could you please tell me anyone who is following the
development or who could give me any hint on how to make out what’s wrong
with my calculation or the Phon module of the code?

Best regards

Zhishuo Huang





*From: *Paolo Giannozzi <p.giannozzi at gmail.com>
*Sent: *Tuesday, March 27, 2018 09:02 PM
*To: *黄志硕 <zhishuohuang at gmail.com>
*Subject: *Re: Different output information in phonon calculation of 'GRID'
and'SPLIT'



It's not "a few minutes", it may take hours. I am no longer following the
development of the phonon code, by the way

Paolo



On Tue, Mar 27, 2018 at 12:36 PM, 黄志硕 <zhishuohuang at gmail.com> wrote:

Dear Prof. Paolo Giannozzi,



I am sorry to bother you through private e-mail, but I have one problem
which I posted on the PWscf-mail list and there is no reply about it. I
don’t know if I express my problem properly or I disobeyed some rules of
posting email on the PWscf-mail list, so I forward to you the e-mail. May I
ask you a few minutes to look into my problem? I would appreciate it a lot.



I am calculating phonon dispersion using two modes of PH module of quantum
espresso. One mode is to split total calculation into calculations of each
irreducible q point (SPLIT), while the other is the GRID calculation as the
demonstrated in the GRID_example, which is to take all the irreducible
representations into consideration. However, the output files shows
different information when I use these two method to calculate phonon
frequency with the same structure and scf input. The main difference is
that in the output of GRID method there is a warning shown below:

##########################################################

     Starting wfc are  267 atomic wfcs



Possibly too few bands at point    1  -0.12500   0.12500   0.12500

Possibly too few bands at point    2   0.37500  -0.37500   0.62500

Possibly too few bands at point    3  -0.37500   0.37500  -0.12500

Possibly too few bands at point    4   0.12500  -0.12500   0.37500

?

?

?

Possibly too few bands at point   87  -1.12500  -0.37500  -0.37500

Possibly too few bands at point   88  -0.62500  -0.87500   0.12500

##########################################################

While there is no such information in the output file of SPLIT method.



The input of GRID method for each irreducible representation is shown below

##########################################################

Phonon of K3C60

&inputph

  tr2_ph=1.0d-17,

  prefix='K3C60',

  ldisp=.true.

  nq1=2, nq2=2, nq3=2

  start_q=2

  last_q=2

  start_irr=?irr_num?,

  last_irr=?irr_num?,

  amass(1)=12

  amass(2)=39.1

  outdir='./',

  fildyn='K3C60.dynG',

  reduce_io = .true.

/

##########################################################

And the input of GRID method after collecting all the information of each
irreducible representation is

##########################################################

Phonon of K3

&inputph

  tr2_ph=1.0d-17,

  prefix='K3C60',

  ldisp=.true.

  nq1=2, nq2=2, nq3=2

  recover=.true.,

  start_q=2

  last_q=2

  amass(1)=12

  amass(2)=39.1

  outdir='./',

  fildyn='K3C60.dynG',

  reduce_io = .true.

/

##########################################################



And the input of SPLIT method is

##########################################################

Phonon of K3C60

&inputph

  tr2_ph=1.0d-17,

  prefix='K3C60',

  ldisp=.true.

  nq1=2, nq2=2, nq3=2

  start_q=2

  last_q=2

  amass(1)=12

  amass(2)=39.1

  outdir='./',

  fildyn='K3C60.dynG',

  reduce_io = .true.

/

##########################################################



Why is there the difference information in the output file for the same
structure and scf input? I will appreciate it if anyone could give me any
information about that.



Best regards

Zhishuo Huang






-- 

Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
<https://maps.google.com/?q=Udine,+via+delle+Scienze+208,+33100+Udine,+Italy&entry=gmail&source=g>
Phone +39-0432-558216 <+39%200432%20558216>, fax +39-0432-558222
<+39%200432%20558222>





-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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