<div dir="ltr"><div>Dear Dr.Hutter</div><div>good moring in Milchbuck<br></div><div><br></div><div>
>For k-point calculations the dipoles are not available and no IR intensities are possible. <br></div><div>>In addition you only get the Gamma point phonon. <br></div><div><br></div><div>Thank you for the kind answer.</div><div><br></div><div>>
For systems like NaCl, what you usually want is a full phonon spectra.<br></div><div><br></div><div></div><div></div><div>I target normal modes in LixMnyOz systems to explain</div><div>changes of Raman modes at cathode of en electric element</div><div>upon a phase transitions, which i could induce using a laser field. <br></div><div>
NaCl is a test ground to understand. <br></div><div><br></div><div>
>you should use specialized software like phonopy that interfaces to CP2K (and many other codes). <br></div><div><br></div><div>Jein: Yes, and No.</div><div><br></div><div>I installed and run phonopy under cygwin-windows.</div><div></div><div>Indeed, usinf CP2K,</div><div>phonopy does compute phonon DOS and PDOS.</div><div><br></div><div>However, a scientific discussion requires understanding what kind of interatomic displacements</div><div>those densities would correspond.</div><div>In this respect, <br></div><div>learning how to condition cp2k is the only way</div><div>towards practical.<br></div><div><br></div><div>Just to have DOS from phonopy and normal modes from cp2k,</div><div>already would be a sufficient playground to impact technology.</div><div><br></div><div>However, conditioninig cp2k to generate relevent (no need to be perfect) normal modes <br></div><div>is the important connection.</div><div><br></div><div>After 30 years in spectroscopy,</div><div>I may say that even computing IR or Raman may not be that important.</div><div></div><div><br></div><div>Yes, computing such is possible using, for example:<br></div><div>git clone <a href="https://github.com/JMSkelton/Phonopy-Spectroscopy.git">https://github.com/JMSkelton/Phonopy-Spectroscopy.git</a></div><div><br></div><div><br></div><div>However, IR-Raman is just a "luxury".</div><div><br></div><div>Correlating normal modes to phonon DOS is sufficient to answer many questions<br></div><div><br></div><div>With best regards,</div><div>Victor<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jan 26, 2022 at 12:26 PM <<a href="mailto:hutter@chem.uzh.ch">hutter@chem.uzh.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi<br>
<br>
The vibrational analysis module is most useful for molecular systems<br>
(molecular crystals) calculated at the Gamma point. In this case<br>
you can also calculate IR intensities through dipole derivatives.<br>
For k-point calculations the dipoles are not available and no<br>
IR intensities are possible. In addition you only get the <br>
Gamma point phonon.<br>
For systems like NaCl, what you usually want is a full phonon spectra.<br>
In this case you should use specialized software like phonopy<br>
that interfaces to CP2K (and many other codes).<br>
<br>
regards<br>
<br>
Juerg Hutter<br>
--------------------------------------------------------------<br>
Juerg Hutter Phone : ++41 44 635 4491<br>
Institut für Chemie E-mail: <a href="mailto:hutter@chem.uzh.ch" target="_blank">hutter@chem.uzh.ch</a> <br>
Universität Zürich <br>
Winterthurerstrasse 190<br>
CH-8057 Zürich, Switzerland<br>
---------------------------------------------------------------<br>
<br>
-----<a href="mailto:cp2k@googlegroups.com" target="_blank">cp2k@googlegroups.com</a> wrote: -----<br>
To: <a href="mailto:cp2k@googlegroups.com" target="_blank">cp2k@googlegroups.com</a><br>
From: "Victor Volkov" <br>
Sent by: <a href="mailto:cp2k@googlegroups.com" target="_blank">cp2k@googlegroups.com</a><br>
Date: 01/25/2022 05:14PM<br>
Subject: Re: [CP2K:16499] Re: IR spectm for NaCl under PBC<br>
<br>
Dear Fabian:<br>
sorry to bother once more. <br>
<br>
Learning from your comments, I optimized the structure (please, see the attached outut) <br>
under<br>
MAX_DR 8.0E-06<br>
RMS_DR 4.0E-06 <br>
MAX_FORCE 1.0E-06<br>
RMS_FORCE 1.0E-07<br>
<br>
This is to run vibrational analysis using the input, as attached.<br>
<br>
In DFT, I do instruct to prinnt moments (as you may see),<br>
but <br>
CP2K reports an error- to be unable to read the moments.<br>
<br>
I wonder if such unexpected "blindness"<br>
is present because the input contains <br>
&KPOINTS<br>
SCHEME MONKHORST-PACK 8 8 8<br>
FULL_GRID .TRUE.<br>
&END KPOINTS<br>
<br>
I include this definition trying to acount the Brullion space structure.<br>
May be this is outside of the scope.<br>
<br>
I wish to understand a bit how CP2K vibrational analysis<br>
accounts (or not) dfinitions of <br>
multiple cell, k-points and periodicity.<br>
<br>
I be thankful if you comment.<br>
Victor<br>
<br>
<br>
On Mon, Jan 24, 2022 at 7:02 PM Victor Volkov <<a href="mailto:volkovskr@gmail.com" target="_blank">volkovskr@gmail.com</a>> wrote:<br>
Dear Fabian;<br>
excellent!<br>
Great learning.<br>
Thank you.<br>
With best regards,<br>
:-)<br>
Victor<br>
<br>
On Mon, Jan 24, 2022 at 4:22 PM <a href="mailto:fabia...@gmail.com" target="_blank">fabia...@gmail.com</a> <<a href="mailto:fabianducry@gmail.com" target="_blank">fabianducry@gmail.com</a>> wrote:<br>
Dear Victor,<br>
<br>
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.<br>
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. <br>
<br>
Cheers,<br>
Fabian<br>
On Sunday, 23 January 2022 at 19:58:05 UTC+1 <a href="mailto:volk...@gmail.com" target="_blank">volk...@gmail.com</a> wrote:<br>
Dear colleagues:<br>
here is the normal mode analysis I could manage by now for NaCl under PBC.<br>
<br>
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.<br>
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.<br>
<br>
When a single cell under PBC, optimization leads to the “right” structure, when ESP 10^-12.<br>
<br>
However, the negative(imaginary) frequencies are many and they are very large.<br>
I may anticipate that the “miss performance” is enhanced due to the PBC.<br>
<br>
Eventhough the results are "devastating",<br>
:-)<br>
nonetheless, I find this might be very good, very helpful – I got an idea.<br>
<br>
Dear Dr. Hutter,<br>
is it possible that CP2K may have an “issue” about positioning a structure <br>
in respect to both, in respect to the FT grind and in respect to the PBC.<br>
Perhaps, there could be a relative mismatch phenomenon, which could stimulate artificial transition states with negative frequencies?<br>
<br>
May be, what I observe is that PBC on the unit cell helps to sense this better?<br>
<br>
<br>
Thank you for your time and for any comments.<br>
<br>
With best regards,Sincerely<br>
Victor<br>
<br>
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[attachment "NaCl_1GPWdiag.out" removed by Jürg Hutter/at/UZH]<br>
[attachment "NaCl_1GPWdiag_F.inp" removed by Jürg Hutter/at/UZH]<br>
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