[Pw_forum] CPO-27-Zn scf not converge

[Paolo Giannozzi]

You need:
- the space group number
- the cell parameters (for the rhombohedral lattice, not the hexagonal one)
- the Wyckoff positions. If the latter are given in hexagonal axis, as
they are here:
  http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-wp-list
  use "rhombohedral=.false."
This is all I know about the specific case of rhombohedral groups

Paolo

On Sat, Jun 4, 2016 at 8:01 PM, Lorenzo Donà <lorechimica91 at hotmail.it> wrote:
> Dear Paolo I have tried a lot of inputs with space_group=148 keyword but the
> structure found is incorrect…
> Or better is correct the number of atom 54 in the cell but the position is
> incorrect.
> Please can you help me to understand the correct input for my system, can
> you tell me how to create the correct structure input using the keyword
> space_group.
> I must tell you that i found problem only for this system for cubic or
> ORTHORHOMBIC system I found NO problem.
> Thanks a lot if you can help me with my problem.
> Dearly
> lorenzo
>
> Il giorno 31 mag 2016, alle ore 21:58, Paolo Giannozzi
> <p.giannozzi at gmail.com> ha scritto:
>
> For the rhombohedral (or trigonal) trigonal lattice, cosab=-0.5 means
> that the angle between any two of the three primitive vectors is 120,
> that is, they lie on a plane. This is why the code complains. By the
> way, here a converter between rhombohedral and hexagonal cells:
> http://qpeng.org/tools/r2h.html, and here a  picture (fig.5):
> http://xrayweb.chem.ou.edu/notes/symmetry.html
>
>
> On Tue, May 31, 2016 at 9:57 AM, Lori 91 <lorechimica91 at hotmail.it> wrote:
>
> Thanks to replay Davide.
> cosab=-0.5 give me an error.
> Thanks a lot dearly
> Lorenzo
>
> Inviato da iPhone
>
> Il giorno 31 mag 2016, alle ore 09:16, Tiana Davide <davide.tiana at epfl.ch>
> ha scritto:
>
> Ciao Lorenzo
>
> I am not sure but one problem could be that you're using cosab 0.5 (60
> degrees) instead of cosab=-0.5 (120 degrees)
> another one (again just a guess) is your cut-off seems to be really low even
> for an ultrasoft pseudopotential.
>
> anyway, you should try with this electron setting
>
>  mixing_mode='local-TF',
>  mixing_beta=0.6,
>
> I've not problem in converging it (using different pseudo though)
>
> Cheers
> Davide
>
> P.S. the last test you can do is to use a bit of smearing, for instance:
>
>  occupations='smearing',
>  smearing='marzari-vanderbilt'
>  degauss=0.05
> ________________________________________
> ------------------------------
>
> Message: 2
> Date: Sun, 29 May 2016 21:11:49 +0200
> From: Lorenzo Don? <lorechimica91 at hotmail.it>
> Subject: [Pw_forum] CPO-27-Zn scf not converge
> To: PWSCF Forum <pw_forum at pwscf.org>
> Message-ID: <BLU436-SMTP367637BD78842FCA03B145CB440 at phx.gbl>
> Content-Type: text/plain; charset="us-ascii"
>
> Dear all can you help me or give me some tips to make scf convergence on
> this calculation:
>
> &control
>   pseudo_dir='/home/utente/Scaricati/espresso-5.4.0/pseudo/'
>   outdir = './',
>   wf_collect = .true.,
>   verbosity= high,
> /
> &system
>   ibrav=  5,
>   a= 25.226, cosab= 0.5,  space_group = 148,
>   nat=  9, ntyp= 4,
>   ecutwfc =15.0,
>   occupations='fixed', smearing='gauss',
>    input_dft= PBE,
> /
> &electrons
>   mixing_mode='plain'
>   diagonalization='david'
>   mixing_beta = 0.01
>   conv_thr= 1.0e-4
>   electron_maxstep=500,
> /
> ATOMIC_SPECIES
> Zn 65.409 Zn.pbe-van.UPF
> C 12.010  C.pbe-van_ak.UPF
> O 16.00   O.pbe-van_ak.UPF
> H 1.00    H.pbe-van_ak.UPF
> ATOMIC_POSITIONS crystal_sg
> C   7.127430447398E-02 -2.455696438145E-01  7.991093030472E-02
> C   1.197468901477E-01 -2.066445045066E-01  2.152449225957E-01
> C   2.117353032357E-01 -1.117780631842E-01  2.553368090727E-01
> C   1.646071563067E-01 -1.528403540257E-01  1.440875844425E-01
> H   1.629458066146E-01 -1.419696182443E-01 -4.760745519579E-03
> Zn  -1.943259345214E-02  2.834354147594E-01  3.060064447988E-01
> O   7.229455751443E-02 -2.290060932141E-01 -9.085450716092E-02
> O   3.018234203718E-02 -2.947952345384E-01  1.422041978763E-01
> O   2.519030126218E-01 -6.097111538485E-02  1.721974260943E-01
> K_POINTS gamma
>
> Thanks a lot to help me
>
> dearly
>
> lorenzo
>
>
>
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> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222