[CP2K-user] [CP2K:17017] Re: SCF Run Not Converged for CELL_OPT of Cu2O

[Matt Watkins]

Hello,
- wrt non-periodic systems it makes no sense to do a cell optimization on a 
non-periodic direction.You are only changing how much vacuum is there and 
that should make no difference if things are OK numerically - this also 
means the cell opt is not well defined (no optimal cell parameters in 
non-periodic directions).
- for the CuO system you need to understand what the electronic structure 
is expected to be - If it is metallic use smearing and diagonalisation. If 
you use +U to get a Mott insulator solution then you need to check the 
occupied states and see that they make sense. Check the SCF loop for 
warning messages about not converging or spurious Mulliken charges. 
Otherwise, check your pw cutoff is large enough to get a sensible stress 
tensor.
Matt

On Friday, 20 May 2022 at 09:56:58 UTC+1 wave... at gmail.com wrote:

> Hi Chelsea
>
> I'm not sure about metal oxides, but the manual does mention that OT 
> converges poorly with metals. I also had to avoid OT for pure Au.
>
> Do you or anyone else know whether CELL_OPT is appropriate for 
> non-periodic systems (e.g., molecules, nanoparticles).
>
> Kind Regards
>
> Sam
> On Thursday, May 19, 2022 at 2:37:22 PM UTC+2 uri... at gmail.com wrote:
>
>> Dear  Marcella
>>
>> Thank you very much for your help and the scf-coverge problem for cel-opt 
>> has been solved. The results are listed as follows:
>> -DIAG would perfectly solve the problem for cel-opt yet the following 
>> geo-opt still fluctuated without converge under same parameter.
>> - tighter EPS_DEFAULT didn't work with OT but would benefit for converge 
>> with DIAG method.
>> - higher PW-cutoff and changing the U_MINUS_J value both failed to 
>> converge the scf cycle with OT method in my cel-opt case
>>
>> Thank you again for your help!
>>
>> Regards
>> Chelsea
>>
>>
>> 在2022年5月19日星期四 UTC+8 20:20:08<Faye Guo> 写道：
>>
>>>
>>> Dear all
>>>
>>> The problem has been solved, the Diagonalisation rather than OT would 
>>> converge the scf cycle and CEL-OPT.
>>>
>>> However, a new one occurred in the following GEO-OPT which could hardly 
>>> converge with an increasing total force and DFT+U energy. I've attached the 
>>> input and output and I would really appreciate the suggestions.
>>>
>>> Thanks in advance. 
>>> Bests
>>>
>>> Chelsea 
>>> 在2022年5月10日星期二 UTC+8 10:23:59<Faye Guo> 写道：
>>>
>>>> Dear  Marcella
>>>>
>>>> Thank you very much for your help. I've watched some of your lectures 
>>>> on youtube which are of great help to me as a very beginner in cp2k and 
>>>> computaional method.
>>>>
>>>> As to my case:
>>>> 1. Smaller U-J value from 5-6.8 still failed to converge the scf cycle
>>>> 2. I'm confused about whether DFT+U method is right for Cu2O 
>>>> optimization as the magnetic moment is only about 0.012uB( data from 
>>>> material project). And I do read some papers discussing Cu2O modeling 
>>>> without +U information 
>>>> 3. I've tried the DIIS minimizer method which did converge the scf 
>>>> cycle but brought about an abnormal GEO-optimization result. I guess this 
>>>> might related to that DIIS method is likely to give an unstable solution
>>>> I'll try the other options to see if there's anyone could make it.
>>>>
>>>> I've uploaded the input and output files for both DIIS and CG methods 
>>>> and I really appreciated your help.
>>>>
>>>> Bests
>>>> Chelsea
>>>> 在2022年5月9日星期一 UTC+8 16:38:08<Marcella Iannuzzi> 写道：
>>>>
>>>>> Dear Chelsea
>>>>>
>>>>> Some things that you can try are:
>>>>> -use diagonalisation instead of OT
>>>>> - use tighter EPS_DEFAULT
>>>>> - higher PW-cutoff
>>>>> - change the U_MINUS_J value
>>>>>
>>>>> Without having the output it is hard to guess what is going on. 
>>>>>
>>>>> Regards
>>>>> Marcella
>>>>>
>>>>> On Sunday, May 8, 2022 at 5:16:12 PM UTC+2 uri... at gmail.com wrote:
>>>>>
>>>>>> Dear All, 
>>>>>>
>>>>>> I've been trying to perform a CELL_OPT for  Cu2O  but the calculation 
>>>>>> sadly cannot converge the SCF cycles. 
>>>>>>
>>>>>>  I tried all possible OT preconditioners with CG as minimizer by cp2k 
>>>>>> 6.1 edition which all failed and spin contamination even occurred under 
>>>>>> full_all condition.  
>>>>>>
>>>>>> I also tried the increase of max_scf from 100 to 400 as well as the 
>>>>>> energy gap from 1*10-4 to 1*10-2, yet neither of them worked.
>>>>>>
>>>>>> So I'm wondering if any else had these issues and found ways to 
>>>>>> overcome them? And the input file is attached as follows.
>>>>>>
>>>>>> Any help would be much appreciated. Thanks in advance. 
>>>>>> Bests
>>>>>>
>>>>>> Chelsea 
>>>>>>
>>>>>

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