[Wien] Cholesky in supercell

Wed Apr 3 10:55:20 CEST 2024

Dear Professor Laurence Marks,

* I returned the mixing parameter value back to 0.2, thanks a lot for the
comprehensive explanation in "Mixing for Dummies";
* I set the new values of the spheres using setrmt –a
Ba:2.10,Ti:1.78,O:1.61 ;
* Then I copied the case.struct_setrmt file to case.structure
* After that, I initialized using the init_lapw -prec 0n -numk 10 -nometal
-ecut .998
* After correct initialization, I started the calculation using the command
run_lapw -ec 0.001 -cc 0.01 -fc 1 -p

I didn't use -it, however, now I got the error 'no energy limits' for L=0
of the Ba atom. At the same time, the value of :DIS was 0.7696, 0.7658,
0.6547, 0.6399, 0.6399.

To build my supercell, I used a tetragonal BaTiO3 cell, not the 1x1x15
structures for which I have the minimized parameters. For the calculation,
I use a small number of k-points in the case.klist I have a 5x3x1 grid set.

Thank you in advance,

Best Regards,

Natalia

On Tue, Apr 2, 2024 at 4:55 AM Laurence Marks <laurence.marks at gmail.com>
wrote:

> Did you follow my suggestion and not use -it? It appears that you did not.
> I would not use it until :DIS is less than 0.05, and perhaps not even then.
> You are still being incomplete about the information you provide:
>
> On Tue, Apr 2, 2024 at 1:34 AM Natalia Andreeva <nvandr at gmail.com> wrote:
>
>> Dear Professor Laurence Marks,
>> Thank you very much for your reply. I will try to reveal the question
>> of what I use for the calculation.
>>
>> * The error occurs immediately when the first calculation cycle has
>> not yet completed.
>> * No, I don't use runsp, the vacuum value is 25au and RMT=5.20
>> * I have a supercell without a defect and correctly calculated SCF
>> with parameters 1x1x15, for which I performed the calculation without
>> runsp. For this structure, the parameters were chosen to be
>> RMT=5.09, Mt(Ba)=2.25, Rt(Ti)=1.74, Rmt(O)=1.58. This structure is an
>> insulator, I also minimized the parameters for it.
>>
> Are you using the same parameters? What k-points are you using? Did you
> optimize the positions then use them for your supercell?
>
>> * I use WIEN2k version 23.2 with ELPA for calculations
>> * So far I do not use minimization, but I plan to do it after
>> receiving the correct calculation of this structure.
>> * I use iterative diagonalization using the -it flag, on the second loop.
>>
>> I tried to reduce the Ba RMT to 2.1 using -ecut .998, however,
>> this resulted in the error 'no energy limits found'. I have reduced
>> the mixing parameter to case.in up to 0.1, and the Cholesky error
>> appeared again on the third calculation cycle.
>>
> Did you do a fresh initialization with the new RMTs? It should not have
> led to a problem in the first iteration.
>
> DO NOT REDUCE THE MIXING PARAMETER, this is fake information. I do not
> know how many times I have had to repeat this, please read the "Mixing for
> Dummies" pdf.
>
> In a few cases it may be appropriate to do "echo 0.005 > .pratt" for the
> very first iteration only. The mixer uses prior information, and when there
> is none it can be too aggressive. (Starting parameters for optimization and
> fixed-point code are always guesswork.)
>
>>
>> Thank you in advance,
>> With Best Regards,
>> Natalia.
>>
>> On Wed, Mar 27, 2024 at 8:21 PM Laurence Marks <laurence.marks at gmail.com>
>> wrote:
>>
>>> You have not provided enough information for a full diagnosis. When does
>>> this occur, right at the beginning? Are you using runsp? How much vacuum?
>>> What RKMAX? Do you have ELPA? What version of Wien2k? K-points?
>>> Minimisation? Which iterative? When are you using the iterative, in the 2nd
>>> cycle?
>>>
>>> Some suggestions:
>>> * Reduce the Ba RMT to 2.1. You may need to use -ecut .998 during
>>> initialization.
>>> * Use a vacuum of at most 1/3 of full unit cell. 20au is often enough,
>>> 30 certainly, 40 is excessive.
>>> * Minimize first you 1x1x15 cell with no vacancy & P4mm symmetry. Check
>>> it is a sensible insulator. If not then everything is wrong.
>>> * Remove, manually the Ti 3d search, as it is less stable.
>>> * Use ELPA not iterative. While iterative may be faster per cycle, it
>>> can lead to more iterations and less stability so the nett is slower. For
>>> certain I would not use it for a surface until I have somewhat converged.
>>> (You have to be in the space of densities where you have ions as against
>>> the initial neutral atoms.)
>>>
>>> --
>>> Professor Laurence Marks (Laurie)
>>> Northwestern University
>>> www.numis.northwestern.edu
>>> https://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en
>>> "Research is to see what everybody else has seen, and to think what
>>> nobody else has thought" Albert Szent-Györgyi
>>>
>>> On Wed, Mar 27, 2024, 21:22 Natalia Andreeva <nvandr at gmail.com> wrote:
>>>
>>>> Dear Win2k users,
>>>>
>>>>  I am trying to calculate a sufficiently large 2x3x15 supercell  based
>>>> on a tetragonal barium titanate (BaTiO3) cell. In this calculation, I
>>>> create an oxygen vacancy and a surface. The calculation is successfully
>>>> initialized with the parameters of atomic spheres equal to Rmt(Ba)=2.30,
>>>> Rmt(Ti)=1.82, Rmt(O)=1.65. However, when I run the calculation with PBE,
>>>> iterative diagonalization, an error appears:
>>>>
>>>> ** Error in Parallel LAPW1
>>>> ** LAPW1 STOPPED
>>>> ** check ERROR FILES!
>>>> Cholesky INFO = 9896
>>>> 'SECLR4' - POTRF (Scalapack/LAPACK) failed.
>>>>
>>>> I tried to find an answer in WIEN2k's letters – among the suggestions
>>>> was rerun the calculation after setting other initial electron density
>>>> parameters (dstart), changing the radii of atomic spheres, and others, but
>>>> they did not help. What could I do to run this calculation correctly?
>>>>
>>>>
>>>> Thank you in advance,
>>>> Best Regards,
>>>> Natalia
>>>>
>>>> Add reaction
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>>
>>
>> --
>> Best Regards,
>> Natalia Andreeva.
>> _______________________________________________
>> Wien mailing list
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>> SEARCH the MAILING-LIST at:
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>>
>
>
> --
> Professor Laurence Marks (Laurie)
> Northwestern University
> Webpage <http://www.numis.northwestern.edu> and Google Scholar link
> <http://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en>
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought", Albert Szent-Györgyi
> _______________________________________________
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> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
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>

-- 
Best Regards,
Natalia Andreeva.
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