[CP2K-user] [CP2K:16511] Re: IR spectm for NaCl under PBC

[fabia...@gmail.com]

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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