[QE-users] ibrav number check

[Giovanni Cantele]

maybe you’re visualising the conventional, rather than the primitive unit cell.
Try to set Display -> Primitive Cell Mode

The bct unit cel should show up.

Giovanni

-- 

Giovanni Cantele, PhD

CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy

e-mail: giovanni.cantele at spin.cnr.it
            gcantele at gmail.com
Phone: +39 081 676910
Skype contact: giocan74
Web page: https://sites.google.com/view/giovanni-cantele

> On 19 Nov 2018, at 19:38, Chan, Edmund <thc208 at exeter.ac.uk> wrote:
> 
> Dear all users,
>  
> I am currently trying to relax a methylammonium lead iodide CH3NH3PbI3 structure which has tetragonal structure I4/mcm. Thus, in my input file, I select ibrav = 7 (body centred teragonal). However, as I visualise the input and output on Xcrysden, the unit cell becomes orthorhombic. Why is that?
>  
>  
> &CONTROL
>                        title = 'MAPI' ,
>                  calculation = 'relax' ,
>                 restart_mode = 'from_scratch' ,
>                       outdir = './' ,
>                   pseudo_dir = './' ,
>                       prefix = 'CH3NH3PbI3' ,
> /
> &SYSTEM
>                        ibrav = 7,
>                    A = 8.83920,
>                    C = 12.6948,
>                          nat = 12,
>                         ntyp = 5,
>                      ecutwfc = 80 ,
>                        ecutrho = 800,
> /
> &ELECTRONS
>             electron_maxstep = 5000 ,
>                     conv_thr = 1.0d-6 ,
>                  mixing_beta = 0.3 ,
> /
> &IONS
>                 ion_dynamics = 'bfgs' ,
> /
> ATOMIC_SPECIES
>     C   12.01070  c_pbesol_v1.2.uspp.F.UPF
>     H    1.00794  H.pbesol-rrkjus_psl.0.1.UPF
>     N   14.00670  N.pbesol-theos.UPF
>    Pb  207.20000  Pb.pbesol-dn-kjpaw_psl.0.2.2.UPF
>     I  126.90450  i_pbesol_v1.uspp.F.UPF
> ATOMIC_POSITIONS alat
>    Pb      0.000000000    0.000000000    0.500000000   
>     I      0.000000000    0.000000000    0.250000000   
>     I      0.294200000    0.205800000    0.500000000   
>     I     -0.294200000   -0.207600000    0.500000000   
>     C      0.544000000    0.921000000    0.784000000   
>     H      0.609200000    1.002100000    0.769900000   
>     H      0.557300000    0.845500000    0.724600000   
>     H      0.551500000    0.875200000    0.864300000   
>     N      0.389000000    0.987000000    0.767000000   
>     H      0.324700000    0.913900000    0.730300000   
>     H      0.381400000    1.068100000    0.734300000   
>     H      0.339300000    0.990800000    0.831000000   
> K_POINTS automatic
>   1 1 1   0 0 0
>  
> Thank you all.
>  
>  
> Kind regards,
>  
> Edmund Chan
> ________________________________________________
> Edmund Chan
> PhD Renewable Energy Student
> Environment & Sustainablity Institute
> College of Engineering, Mathematics and Physical Sciences
> University of Exeter, Penryn Campus
> Penryn, Cornwall
> United Kingdom
> TR10 9FE
> 
> Tel: +44 (0)7455 235 701 <tel:+44%207455%20235%20701>
> Email: thc208 at exeter.ac.uk <mailto:thc208 at exeter.ac.uk>
> LinkedIn: https://uk.linkedin.com/in/edmundchan1 <https://uk.linkedin.com/in/edmundchan1>
> <image002.jpg>
>  
> <image003.gif>
>  
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