[CP2K-user] [CP2K:16512] Re: IR spectm for NaCl under PBC

[Victor Volkov]

Dear Fabian:
Dear Dr. Hutter:

is it possible that CP2K is present not to follow the input instructons?

*According to my instructions (pleas, see attached)*
*in the MOTION section there are instructions*
    MAX_DR    8.0E-07
    RMS_DR    4.0E-07
    MAX_FORCE 1.0E-07
    RMS_FORCE 1.0E-08


*but *
*as Fabian has noticed:*

The output you attached shows for step 28:
  Max. gradient              =         0.0002958006
  Conv. limit for gradients  =         0.0004500000
  Conv. in gradients         =                  YES

So that output is for MAX_FORCE 4.5E-4 and not 1.0E-7. You should also
decrease EPS_SCF (to 1e-7 or 1e-8) and probably EPS_DEFAULT.


*Is it possible that there is a bug *
*that prevents a certain level of precision?*

Thank you.
With best regards.

Victor




On Thu, Jan 27, 2022 at 12:00 PM fabia... at gmail.com <fabianducry at gmail.com>
wrote:

> Dear Viktor,
>
> The output you attached shows for step 28:
>   Max. gradient              =         0.0002958006
>   Conv. limit for gradients  =         0.0004500000
>   Conv. in gradients         =                  YES
>
> So that output is for MAX_FORCE 4.5E-4 and not 1.0E-7. You should also
> decrease EPS_SCF (to 1e-7 or 1e-8) and probably EPS_DEFAULT.
>
> Fabian
>
> On Wednesday, 26 January 2022 at 21:12:03 UTC+1 volk... at gmail.com wrote:
>
>> Dear Fabian:
>> please forgive me
>>
>> *If I set*
>>     OPTIMIZER BFGS
>>
>>     MAX_DR    8.0E-06
>>     RMS_DR    4.0E-06
>>     MAX_FORCE 1.0E-06
>>     RMS_FORCE 1.0E-07
>> *then the forces are*
>> ATOMIC FORCES in [a.u.]
>>  # Atom   Kind   Element          X              Y              Z
>>       1      1      Na          0.00000796     0.00000796     0.00000796
>>       2      1      Na          0.00000796     0.00001127     0.00001127
>>       3      1      Na          0.00001127     0.00000796     0.00001127
>>       4      1      Na          0.00001127     0.00001127     0.00000796
>>       5      2      Cl          0.00000052     0.00000052     0.00000052
>>       6      2      Cl          0.00000052     0.00000052     0.00000052
>>       7      2      Cl          0.00000052     0.00000052     0.00000052
>>       8      2      Cl          0.00000052     0.00000052     0.00000052
>>  SUM OF ATOMIC FORCES           0.00004056     0.00004056     0.00004056
>>     0.00007026
>>
>> *and the soectrum is terrible (please, see the attached xxx_F.out)*
>>
>> *Then I try to instruct more strict convregence by*
>>     OPTIMIZER BFGS
>>     MAX_DR    8.0E-07
>>     RMS_DR    4.0E-07
>>     MAX_FORCE 1.0E-07
>>     RMS_FORCE 1.0E-08
>>
>> *but the forces deteriorate*
>> ATOMIC FORCES in [a.u.]
>>  # Atom   Kind   Element          X              Y              Z
>>       1      1      Na          0.00009945     0.00009945     0.00009945
>>       2      1      Na          0.00025879    -0.00001513    -0.00001513
>>       3      1      Na         -0.00001519     0.00025872    -0.00001518
>>       4      1      Na         -0.00001513    -0.00001513     0.00025879
>>       5      2      Cl          0.00031492     0.00004422     0.00004422
>>       6      2      Cl          0.00024177     0.00024177     0.00024177
>>       7      2      Cl          0.00004422     0.00004422     0.00031492
>>       8      2      Cl          0.00004422     0.00031492     0.00004422
>>  SUM OF ATOMIC FORCES           0.00097305     0.00097303     0.00097305
>>     0.00168536
>>
>> *I attach the optimization inp and out pair.*
>> *I donot see what is wrong?*
>>
>> *May be GPW and BFGS are not for such optimizations?   *
>> *Thank you.*
>> *Victor*
>>
>>
>>
>> On Mon, Jan 24, 2022 at 4:22 PM fabia... at gmail.com <fabia... 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
>>>>
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