[CP2K-user] [CP2K:16501] Re: IR spectm for NaCl under PBC

[hutter at chem.uzh.ch]

Hi

The vibrational analysis module is most useful for molecular systems
(molecular crystals) calculated at the Gamma point. In this case
you can also calculate IR intensities through dipole derivatives.
For k-point calculations the dipoles are not available and no
IR intensities are possible. In addition you only get the 
Gamma point phonon.
For systems like NaCl, what you usually want is a full phonon spectra.
In this case you should use specialized software like phonopy
that interfaces to CP2K (and many other codes).

regards

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie                E-mail: hutter at chem.uzh.ch 
Universität Zürich                  
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp2k at googlegroups.com wrote: -----
To: cp2k at googlegroups.com
From: "Victor Volkov" 
Sent by: cp2k at googlegroups.com
Date: 01/25/2022 05:14PM
Subject: Re: [CP2K:16499] Re: IR spectm for NaCl under PBC

Dear Fabian:
sorry to bother once more. 

Learning from your comments, I optimized the structure (please, see the attached outut) 
under
    MAX_DR    8.0E-06
    RMS_DR    4.0E-06    
    MAX_FORCE 1.0E-06
    RMS_FORCE 1.0E-07

This is to run vibrational analysis using the input, as attached.

In DFT, I do instruct to prinnt moments (as you may see),
but 
CP2K reports an error- to be unable to read the moments.

I wonder if such unexpected "blindness"
is present because the input contains 
   &KPOINTS
   SCHEME  MONKHORST-PACK  8 8 8
   FULL_GRID  .TRUE.
   &END KPOINTS

I include this definition trying to acount the Brullion space structure.
May be this is outside of the scope.

I wish to understand a bit how CP2K vibrational analysis
accounts (or not) dfinitions of 
multiple cell, k-points and periodicity.

I be thankful if you comment.
Victor


On Mon, Jan 24, 2022 at 7:02 PM Victor Volkov <volkovskr at gmail.com> wrote:
Dear Fabian;
excellent!
Great learning.
Thank you.
With best regards,
:-)
Victor

On Mon, Jan 24, 2022 at 4:22 PM fabia... at gmail.com <fabianducry at gmail.com> wrote:
Dear Victor,

You need a much tighter convergence criterion for the optimization prior to the vibrational analysis. You increased  MAX_FORCE to 5e-3 (guessing from the output), instead you have to decrease it to at least 1e-5, maybe even lower.
CP2K prints the forces for the replica in the output. The forces under "Minimum Structure - Energy and Forces:" should be more or less 0 and considerably differ between the other images. Currently you are computing the vibrational analysis from almost pure noise.  

Cheers,
Fabian
On Sunday, 23 January 2022 at 19:58:05 UTC+1 volk... at gmail.com wrote:
Dear colleagues:
here is the normal mode analysis I could manage by now for NaCl under PBC.

There is only one unit cell: previously, I reported that I could not configure CP2K to reproduce NaCl structure using multiple cells 2 2 2.
There are strange distortions, which I did confirm to sustain under different CUTOFF values (1000 and 600), and regardless if dispersion is switched off or not.

When a single cell under PBC, optimization leads to the “right” structure, when ESP 10^-12.

However, the negative(imaginary) frequencies are many and they are very large.
I may anticipate that the “miss performance” is enhanced due to the PBC.

Eventhough the results are "devastating",
:-)
nonetheless, I find this might be very good, very helpful – I got an idea.

Dear Dr. Hutter,
is it possible that CP2K may have an “issue” about positioning a structure 
in respect to both, in respect to the FT grind and in respect to the PBC.
Perhaps, there could be a relative mismatch phenomenon, which could stimulate artificial transition states with negative frequencies?

May be, what I observe is that PBC on the unit cell helps to sense this better?


Thank you for your time and for any comments.

With best regards,Sincerely
Victor
  
  -- 
 You received this message because you are subscribed to a topic in the Google Groups "cp2k" group.
 To unsubscribe from this topic, visit https://groups.google.com/d/topic/cp2k/bAo0CtNixo8/unsubscribe.
 To unsubscribe from this group and all its topics, send an email to cp2k+unsubscribe at googlegroups.com.
 To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/dd5077c3-4bac-4fa0-a81d-ef779f43e157n%40googlegroups.com.
    
  -- 
 You received this message because you are subscribed to the Google Groups "cp2k" group.
 To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
 To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/CAK%2B-SSibTi1ta1PQ4kavUwtH0r96DixFA4KsrwoFxs-B%2B0%3D32Q%40mail.gmail.com.
 

[attachment "NaCl_1GPWdiag.out" removed by Jürg Hutter/at/UZH]
[attachment "NaCl_1GPWdiag_F.inp" removed by Jürg Hutter/at/UZH]

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/OF0067458D.4DFE9FC1-ONC12587D6.0033DC79-C12587D6.0033DC7B%40lotus.uzh.ch.