[Pw_forum] problem with ibrav=13 again

[Gabriele Sclauzero]

hania djani-ait aissa wrote:
> Dear all,
> i am doing calculation on C2/m monoclinic base centered structure. 
> Infortunately, things don't work;no symmetry in the output and weird 
> structure viewed bu Xcrysden.I checked the coordinates with an other 
> code (Wien2k) where everything seemed to go well, giving the exact 
> number of symmetry operations and the expected structure in Xcrysden. by 
> the way, i am working on Pwscf version 3.2, where the bug ibrav=13 is 
> fixed for good!!!
> please help me to figure out the problem, 

If you want to be helped you should send the full input file (I don't understand why you 
omit some of the atomic positions, which could be relevant to solve your problem).

Your (partial) structure does not look so wierd to me when inspecting it with xcrysden 
(but I don't know this system, so maybe I'm wrong). Maybe you did not find the symmetry 
you expected because you specified the atomic postion with too low accuracy, so try to 
specify them with more significant digits (at least 6 or more) and try running pw.x again.

GS


> here is my input file:
> 
>  &control
>     calculation  = 'scf'
>     restart_mode = 'from_scratch'
>     pseudo_dir   = '/home/hania//pseudo/
>     outdir       = '/home/hania//tmp/'
>  /
>  &system
>     ibrav=13
>     celldm(1)=31.067,
>     celldm(2)=0.234,
>     celldm(3)=0.5,
>     celldm(4)=-0.213,
>     nat=18
>     ntyp=3
>     ecutwfc=35.0
>     ecutrho=200.0,
>     occupations = 'fixed'
>    
>  /
>  &electrons
>     conv_thr = 1e-6,
>     mixing_beta=0.7,
>  /
> ATOMIC_SPECIES
>  
>   W     183.84    W.pz-bhs.UPF
>   Bi    208.98    083-Bi-ca-d-vgrp_ji.uspp.UPF
>   O     15.9994   O.pz-van_ak.UPF
>  
> ATOMIC_POSITIONS alat
>  W  0.4981    0.117     0.15035
>  W  0.5019    0.117     0.34965
>  Bi 0.3341    0.000     0.46565     
>  Bi 0.6659    0.000     0.03435
>  Bi 0.3213    0.000     0.1975
>  …………………………………………………..
>  …………………………………………………….
> 
>  …………………………………………………….
> 
>  O  0.5054    0.000     0.34435
>  O  0.5753    0.117     0.25435
>  O  0.4247    0.117     0.24565
>  O  0.5696    0.117     0.0867
>  O  0.4304    0.117     0.4133
>  O  0.3972    0.117     0.08225
>  O  0.6028    0.117     0.41775
>  
>  K_POINTS {automatic}
>   3 6 6 1 1 1
>  
> 
> thanks in advance,
>  
> Hania Djani-Ait Aissa
> ph.d. student
>  
> Centre de Développement des Technologies Avancées (CDTA)
> Baba Hassen Alger, Algérie
> Division Milieux Ionisées & Lasers
> Phone: (+213)21351044; Fax:(+213)21351039
> http://www.cdta.dz
>  
> 
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| Gabriele Sclauzero, PhD Student                  |
| c/o:   SISSA & CNR-INFM Democritos,              |
|        via Beirut 2-4, 34014 Trieste (Italy)     |
| email: sclauzer at sissa.it                         |
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| skype: gurlonotturno                             |
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