[Pw_forum] CPO-27-Zn scf not converge

[Lorenzo Donà]

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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>> 
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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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