[Pw_forum] Question on SCF

[Heng Luo]

My system is a perovskite structure. I calculate two cases, without oxygen
vacancy and with oxygen vacancy.
I tried spin polarized setup later, it is still not working.
In the &electron part, I have changed electron_maxstep to 1000.
I guess the problem maybe it is metal but I treat is as insulator. So I
indicate the "occupation" and use a "degauss = 0.05". But it is very
strange that it is working for without oxygen vacancy case. For with oxygen
vacancy it fails.


It happens at the first dynamics step. I will check the time-step.
And may the high threshold (1.d-4) the scf forces affect? I just want to
speed it up. For the smearing, I see other people use 0.05 Ry and my system
should be metallic.
I changed the default diagonalisation because Davidson diagonalisation will
fail sometime. CG is slow but it is said that it never failed.

I have attached my input and output here.

Thank you very much!

Heng



On Thu, Jan 23, 2014 at 4:22 PM, Feng, Zimin <Feng.Zimin at ireq.ca> wrote:

>  if it is magnetic, you'd better use spin polarized setup. -- this is all
> i can say for now.
> also, you are the only one that is concerned about it!
> did you change the source code of QE in order to make the maximum allowed
> value of electron_maxstep to be more than 100?
> fzm
>
>  ------------------------------
> *De :* pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] *De
> la part de* Heng Luo
> *Envoyé :* 23 janvier 2014 16:05
> *À :* pw_forum at pwscf.org
> *Objet :* [Pw_forum] Question on SCF
>
>  To whom it concerns,
>
> I am trying to use QuantumEspresso to do some geometry optimization
> calculations. But my self-consistency does not converge. I have tried your
> ideas in the official site, but it is still not working. Can you give me
> some suggestion?
>
> Here is my input data:
>
>  &control
>
>   calculation       = 'vc-relax'
>
>   pseudo_dir        = '/home/frankhen/espresso/pseudo/'
>
>   restart_mode      = 'from_scratch'
>
>   prefix            = 'sto',
>
>   verbosity         = 'high',
>
> /
>
> &system
>
>   ibrav              = 0
>
>   celldm(1)          = 0
>
>   nat                = 39,
>
>   ntyp               = 5,
>
>   ecutwfc            = 25.0,
>
>   ecutrho            = 250.0,
>
>   occupations        = 'smearing',
>
>   degauss            = 0.05,
>
> /
>
> &electrons
>
>   conv_thr           = 1.D-4,
>
>   electron_maxstep   = 10000,
>
>   mixing_beta = 0.3,
>
>   diagonalization = 'cg',
>
> /
>
> &ions
>
> /
>
> &CELL
>
>    cell_dynamics = 'damp-w' ,
>
>    press = 0.00 ,
>
>    wmass =  0.00700000
>
>  /
>
> ATOMIC_SPECIES
>
>   Fe     55.85       Fe.pbe-sp-van_ak.UPF
>
>   Co     58.93       Co.pbe-sp-van.UPF
>
>   La     138.91      La.pbe-nsp-van.UPF
>
>   Sr     87.62       Sr.pbe-nsp-van.UPF
>
>   O      15.9994     O.pbe-van_ak.UPF
>
> ATOMIC_POSITIONS
>
> Fe 0.5 0 0 1 1 1
>
> Fe 0 0.5 0 1 1 1
>
> Fe 0 0 0.5 1 1 1
>
> Fe 0 0.5 0.5 1 1 1
>
> Fe 0.5 0 0.5 1 1 1
>
> Fe 0.5 0.5 0 1 1 1
>
> Co 0 0 0 1 1 1
>
> Co 0.5 0.5 0.5 1 1 1
>
> La 0.25 0.25 0.25 1 1 1
>
> La 0.25 0.75 0.25 1 1 1
>
> La 0.25 0.25 0.75 1 1 1
>
> La 0.75 0.25 0.75 1 1 1
>
> La 0.75 0.75 0.25 1 1 1
>
> La 0.75 0.75 0.75 1 1 1
>
> Sr 0.75 0.25 0.25 1 1 1
>
> Sr 0.25 0.75 0.75 1 1 1
>
> O 0 0.25 0 1 1 1
>
> O 0 0 0.25 1 1 1
>
> O 0.75 0 0 1 1 1
>
> O 0.5 0.25 0 1 1 1
>
> O 0.5 0 0.25 1 1 1
>
> O 0.25 0.5 0 1 1 1
>
> O 0 0.75 0 1 1 1
>
> O 0 0.5 0.25 1 1 1
>
> O 0.25 0 0.5 1 1 1
>
> O 0 0.25 0.5 1 1 1
>
> O 0 0 0.75 1 1 1
>
> O 0.25 0.5 0.5 1 1 1
>
> O 0 0.75 0.5 1 1 1
>
> O 0 0.5 0.75 1 1 1
>
> O 0.75 0 0.5 1 1 1
>
> O 0.5 0.25 0.5 1 1 1
>
> O 0.5 0 0.75 1 1 1
>
> O 0.75 0.5 0 1 1 1
>
> O 0.5 0.75 0 1 1 1
>
> O 0.5 0.5 0.25 1 1 1
>
> O 0.75 0.5 0.5 1 1 1
>
> O 0.5 0.75 0.5 1 1 1
>
> O 0.5 0.5 0.75 1 1 1
>
> K_POINTS {automatic}
>
>   2 2 2  0 0 0
>
> CELL_PARAMETERS {angstrom}
>
> 14.74 0.0 0.0
>
> 0.0 14.74 0.0
>
> 0.0 0.0 14.74
>
>
> Sincerely,
>
> Heng
>
> --
> Heng Luo
> Ph.D candidate
> Department of Mechanical Engineering
> 15 Saint Mary's Street, Room 122
> Brookline, Ma 02446
> Boston University
>
> Office: 617-353-8469
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>



-- 
Heng Luo
Ph.D candidate
Department of Mechanical Engineering
15 Saint Mary's Street, Room 122
Brookline, Ma 02446
Boston University

Office: 617-353-8469
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