[Pw_forum] CPO-27-Zn scf not converge

[Paolo Giannozzi]

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