Re: [Pw_forum] difference in output from dynmat.x and matdyn.x

[Lorenzo Paulatto]

Dear Sridhar,
normally the sum rules imposed by matdyn are enough to set the acoustic 
bands at gamma to exactly zero. If this is not the case, it normally 
means that you have some negative frequency somewhere else in the 
q-point grid. Please check the other matdyn files to see if this is the 
case: the frequencies are at the end of the file.


kind regards


On 17/11/14 02:03, Sridhar Sadasivam wrote:

Dear Stefano,

Thanks for your reply. Here are the frequencies at gamma point when I 
set zasr and asr to 'simple'

  -12.8981  -12.8981   -4.5998  142.6073  168.0267  168.0267
  249.0588  249.0588  340.4760  344.4668  379.2589  379.2589
  417.0274  417.0274  429.6273  457.2113  657.8050  657.8050
  746.0641  755.8553  755.8553 1032.5200 1032.5200 1037.0491
 1048.5362 1136.7760 1136.7760

Thanks,
Sridhar

On Sun, Nov 16, 2014 at 5:25 AM, stefano de gironcoli 
mailto:degir...@sissa.it>> wrote:


dear Sridhar Sadasivam
  can you try to set zasr and asr to 'simple' in the
q2r+matdyn case and report the results ?
  thanks
stefano



On 11/15/2014 11:49 PM, Sridhar Sadasivam wrote:

Dear espresso users and developers,

I am trying to obtain the phonon dispersion of alpha-quartz
(SiO2) which has a 9 atom unit cell. I ran ph.x on a 3 x 3 x 3
q-point grid. I am seeing some strange behavior where there seems
to be a difference in the frequencies output from dynmat.x and
matdyn.x. I will explain my problem below.

I diagonalized the dynamical matrix at the gamma point using
dynmat.x with acoustic sum rule set to crsytal. Since SiO2 is a
polar material, LO-TO splitting will need to be considered at the
gamma point but I am ignoring it currently (I did not specify any
direction for LO-TO splitting in the dynmat.x input). This gave
me the following 27 frequencies (in cm^-1) at the gamma point:
(0,0,0, 152.24, 175.57, 175.57, 256.32, 256.32, 341.09, 354.41,
376.86, 376.86, 419.01, 419.01, 435.37, 455.70, 659.12, 659.12,
744.54, 754.62, 1034.38, 1034.38, 1040.20, 1051.12, 1139.60,
1139.60)

I also used q2r.x (with zasr = 'crystal') to obtain the force
constants and then used matdyn.x (with asr = 'crystal') to obtain
the frequencies at the gamma point. However with matdyn.x, I
obtain the following frequencies at the gamma point:
(-29.4088,-22.2535,-22.2535,152.2412,175.8141,175.8141, 256.3373,
256.3373, 341.0892, 355.4227, 376.0495 , 376.0495, 418.6344,
418.6344, 435.3710, 453.6862, 659.7607, 659.7607, 746.4843,
754.8867, 754.8867, 1034.1751, 1034.1751, 1039.7590, 1051.1207,
1139.8191, 1139.8191)

Could someone please explain why I am getting imaginary
frequencies from matdyn.x while dynmat.x gives real frequencies
at the same q-point (gamma in this case)?

Thanks,
Sridhar
Purdue University



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--
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
+33 (0)1 44 275 084 / skype: paulatz
http://www-int.impmc.upmc.fr/~paulatto/
23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05

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Re: [Pw_forum] difference in output from dynmat.x and matdyn.x

[Sridhar Sadasivam]

Dear Stefano,

Thanks for your reply. Here are the frequencies at gamma point when I set
zasr and asr to 'simple'
  -12.8981  -12.8981   -4.5998  142.6073  168.0267  168.0267
  249.0588  249.0588  340.4760  344.4668  379.2589  379.2589
  417.0274  417.0274  429.6273  457.2113  657.8050  657.8050
  746.0641  755.8553  755.8553 1032.5200 1032.5200 1037.0491
 1048.5362 1136.7760 1136.7760

Thanks,
Sridhar

On Sun, Nov 16, 2014 at 5:25 AM, stefano de gironcoli 
wrote:

>  dear Sridhar Sadasivam
>   can you try to set zasr and asr to 'simple' in the q2r+matdyn case
> and report the results ?
>   thanks
> stefano
>
>
>
> On 11/15/2014 11:49 PM, Sridhar Sadasivam wrote:
>
> Dear espresso users and developers,
>
>  I am trying to obtain the phonon dispersion of alpha-quartz (SiO2) which
> has a 9 atom unit cell. I ran ph.x on a 3 x 3 x 3 q-point grid. I am seeing
> some strange behavior where there seems to be a difference in the
> frequencies output from dynmat.x and matdyn.x. I will explain my problem
> below.
>
>  I diagonalized the dynamical matrix at the gamma point using dynmat.x
> with acoustic sum rule set to crsytal. Since SiO2 is a polar material,
> LO-TO splitting will need to be considered at the gamma point but I am
> ignoring it currently (I did not specify any direction for LO-TO splitting
> in the dynmat.x input). This gave me the following 27 frequencies (in
> cm^-1) at the gamma point: (0,0,0, 152.24, 175.57, 175.57, 256.32, 256.32,
> 341.09, 354.41, 376.86, 376.86, 419.01, 419.01, 435.37, 455.70, 659.12,
> 659.12, 744.54, 754.62, 1034.38, 1034.38, 1040.20, 1051.12, 1139.60,
> 1139.60)
>
>  I also used q2r.x (with zasr = 'crystal') to obtain the force constants
> and then used matdyn.x (with asr = 'crystal') to obtain the frequencies at
> the gamma point. However with matdyn.x, I obtain the following frequencies
> at the gamma point: (-29.4088,-22.2535,-22.2535,152.2412,175.8141,175.8141,
> 256.3373, 256.3373, 341.0892, 355.4227, 376.0495 , 376.0495, 418.6344,
> 418.6344, 435.3710, 453.6862, 659.7607, 659.7607, 746.4843, 754.8867,
> 754.8867, 1034.1751, 1034.1751, 1039.7590, 1051.1207, 1139.8191, 1139.8191)
>
>  Could someone please explain why I am getting imaginary frequencies from
> matdyn.x while dynmat.x gives real frequencies at the same q-point (gamma
> in this case)?
>
>  Thanks,
> Sridhar
> Purdue University
>
>
>
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Re: [Pw_forum] error in routine davcio (10) when -npool is used

[Reza Behjatmanesh-Ardakani]

Dear friends
The problem was solved. It was related to the k-point definition.
Now, I can use -npool option without any problem.

With the Best Regards

   Reza Behjatmanesh-Ardakani
   Associate Professor of Physical Chemistry
   Address:
   Department of Chemistry,
   School of Science,
   Payame Noor University (PNU),
   Ardakan,
   Yazd,
   Iran.
   E-mails: 
  1- reza_b_...@yahoo.com (preferred),
  2- behjatman...@pnu.ac.ir, 
  3- reza.b@gmail.com.


On Sat, 11/15/14, Reza Behjatmanesh-Ardakani  wrote:

 Subject: error in routine davcio (10) when -npool is used
 To: pw_forum@pwscf.org
 Date: Saturday, November 15, 2014, 2:25 PM
 
 Dear Friends
 I have compiled QE5.1 by mpiifort/icc/ifort 2015 and run one
 test.
 everything is OK for fftw3x_cdft_lp64.a, scalapack, and
 openmp libraries.
 Only for -npool parallelization level, I get error in final
 section of my output.
 
 My command in bash terminal is :
 
 1- export OMP_NUM_THREADS=2
 2- mpirun -np 24 -hosts Astek,client2
 /home/espresso-5.1/bin/pw.x -npool 2 -inp tio2.in >
 tio2.out
 
 With the Best Regards
 
    Reza Behjatmanesh-Ardakani
    Associate Professor of Physical Chemistry
    Address:
    Department of Chemistry,
    School of Science,
    Payame Noor University (PNU),
    Ardakan,
    Yazd,
    Iran.
    E-mails: 
           1- reza_b_...@yahoo.com
 (preferred),
           2- behjatman...@pnu.ac.ir,
 
           3- reza.b@gmail.com.

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Re: [Pw_forum] difference in output from dynmat.x and matdyn.x

[stefano de gironcoli]

dear Sridhar Sadasivam
  can you try to set zasr and asr to 'simple' in the q2r+matdyn 
case and report the results ?

  thanks
stefano


On 11/15/2014 11:49 PM, Sridhar Sadasivam wrote:

Dear espresso users and developers,

I am trying to obtain the phonon dispersion of alpha-quartz (SiO2) 
which has a 9 atom unit cell. I ran ph.x on a 3 x 3 x 3 q-point grid. 
I am seeing some strange behavior where there seems to be a difference 
in the frequencies output from dynmat.x and matdyn.x. I will explain 
my problem below.


I diagonalized the dynamical matrix at the gamma point using dynmat.x 
with acoustic sum rule set to crsytal. Since SiO2 is a polar material, 
LO-TO splitting will need to be considered at the gamma point but I am 
ignoring it currently (I did not specify any direction for LO-TO 
splitting in the dynmat.x input). This gave me the following 27 
frequencies (in cm^-1) at the gamma point: (0,0,0, 152.24, 175.57, 
175.57, 256.32, 256.32, 341.09, 354.41, 376.86, 376.86, 419.01, 
419.01, 435.37, 455.70, 659.12, 659.12, 744.54, 754.62, 1034.38, 
1034.38, 1040.20, 1051.12, 1139.60, 1139.60)


I also used q2r.x (with zasr = 'crystal') to obtain the force 
constants and then used matdyn.x (with asr = 'crystal') to obtain the 
frequencies at the gamma point. However with matdyn.x, I obtain the 
following frequencies at the gamma point: 
(-29.4088,-22.2535,-22.2535,152.2412,175.8141,175.8141, 256.3373, 
256.3373, 341.0892, 355.4227, 376.0495 , 376.0495, 418.6344, 418.6344, 
435.3710, 453.6862, 659.7607, 659.7607, 746.4843, 754.8867, 754.8867, 
1034.1751, 1034.1751, 1039.7590, 1051.1207, 1139.8191, 1139.8191)


Could someone please explain why I am getting imaginary frequencies 
from matdyn.x while dynmat.x gives real frequencies at the same 
q-point (gamma in this case)?


Thanks,
Sridhar
Purdue University



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[Pw_forum] a lot of negative phonons

[Muhammad Adnan]

Hello everyone
i am beginner of Q-E and was previously working with VASP.
i am calculating phonons for TiO2 anatase but i always get a lot of
negative frequencies. i have even used very dense KP grid and high cutoff
for wfc and c.density (60 and 700) but the problem persists.
if optimize the same structure with VASP and compute phonons then i do not
get any negative frequency.
what could be the possible reason for these negative phonons computed by
Q-E and not by vasp? and how can i improve my calculations? please someone
help me.
kind regards
Adnan
UFJF
Brazil
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