[Pw_forum] vc-relax analysis doubt

[Ricardo Afonso]

I was running another test where I changed:

mixing_beta = 0.5
diag_thr_init = 1.0D-6
upscale = 1000

And it converged pretty fast after 5 bfgs steps.

Thank you all for the help.


On 31 August 2017 at 18:44, Ricardo Afonso <ricardo at df.ufscar.br> wrote:

> Dear Kevin May,
>
> Thanks a lot for your answer. I will try it again using your advice.
>
> Kind Regards,
>
> Afonso.
>
> On 31 August 2017 at 15:54, Kevin May <kmay at mit.edu> wrote:
>
>> Hi Ricardo
>>
>> If I understand correctly, you are saying that you no longer get scf
>> convergence after a few bfgs steps. This can be a frustrating problem, but
>> it has been mentioned on this forum before that after you have tried
>> changing things like smearing (yours is very small, why?) and mixing_beta
>> (sometimes going down to 0.2-0.3 helps), a useful thing to try is setting
>> scf_must_converge = .false. (see PW input file description).
>>
>> Scf convergence can be very sensitive to changes in the atomic positions,
>> so if you just "power through" an intermediate geometry you might start
>> getting scf convergence again after another bfgs step. You want to keep an
>> eye on it to make sure it was just a one-time issue, and that you get scf
>> convergence in the bfgs steps that follow
>> ​ (i.e. be careful).​
>>
>>
>> Good luck.
>>
>> On 31 August 2017 at 15:28, Ricardo Afonso <ricardo at df.ufscar.br> wrote:
>>
>> > Dear Lorenzo,
>> >
>> > I was not asking to someone to recompile my code and did what I have
>> just
>> > done. By other reason, what I'm looking for is if there is any error in
>> > what I have just done, in terms of my input file. For example, changing
>> > upscale may bring some difficult to the code to keep the convergence.
>> > I did not mean to anyone testing my code or something like that. I'm
>> sorry
>> > if that is what sounded. Anyway, I have gone through a good piece of
>> this
>> > forum, but it does not seem that anyone came across the fact that after
>> a
>> > few 'bfgs' cycles the limit of 'scf' cycles is reached. I'm open as wall
>> > for any reference, book, video or website of help, once this "error"
>> keeps
>> > coming up for my structures.
>> >
>> > Otherwise, thank you for your answer.
>> >
>> > Regards.
>> >
>> > --
>> > Ricardo Afonso
>> > Student of Magnetism and Superconductivity Group
>> > Federal University of Sao Carlos
>> >
>> > _______________________________________________
>> > Pw_forum mailing list
>> > Pw_forum at pwscf.org
>> > http://pwscf.org/mailman/listinfo/pw_forum
>> >
>>
>> --
>> Kevin May
>> PhD Candidate
>> Department of Mechanical Engineering, MIT
>>
>
>
>
> --
> Ricardo Afonso
> Student of Magnetism and Superconductivity Group
> Federal University of Sao Carlos
>



-- 
Ricardo Afonso
Student of Magnetism and Superconductivity Group
Federal University of Sao Carlos
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