[Pw_forum] space group bug?

[Vincenzo Verdolino]

It is not a bug. If you check your input file and you change the ireducible zone representation you should look at your input original structure. If you run an scf calculation and you look at the output you have a changed representation which is by default the minimal one. If you carefully look at the atomic distances you will find your cell parameters.

I know it's quite annoing :-) but you get used to

Sent from my iPhone

> On 28/ago/2014, at 18:50, Tommaso Francese <neutrinofrancese at gmail.com> wrote:
> 
> Dear all QE users,
> i tried to simulate a crystal structure of silicon with symmetry space group Fd-3m, where the input was:
> 
> &CONTROL
>                 calculation = 'scf' ,
>                      outdir = '/home/***/espresso-5.1/tmp/' ,
>                  pseudo_dir = '/home/***/upf_files/' ,
>                      prefix = 'si' ,
> /
> &SYSTEM
>                       ibrav = 2,
>                           A = 5.43 ,
>                           B = 5.43 ,
>                           C = 5.43 ,
>                       cosAB = 0 ,
>                       cosAC = 0 ,
>                       cosBC = 0 ,
>                         nat = 8,
>                        ntyp = 1,
>                     ecutwfc = 60 ,
> /
> &ELECTRONS
> /
> ATOMIC_SPECIES
>   Si   28.08550  Si.pz-vbc.UPF 
> ATOMIC_POSITIONS crystal 
>   Si      0.000000000    0.000000000    0.000000000    
>   Si     -0.000000000    0.500000000    0.500000000    
>   Si      0.500000000    0.500000000    0.000000000    
>   Si      0.500000000   -0.000000000    0.500000000    
>   Si      0.750000000    0.250000000    0.750000000    
>   Si      0.250000000    0.250000000    0.250000000    
>   Si      0.250000000    0.750000000    0.750000000    
>   Si      0.750000000    0.750000000    0.250000000    
> K_POINTS automatic 
>  1 1 1   1 1 1 
> 
> i don’t know why, but when i try to visualize both the Input file and Output file with XcrySden or J-ICE, the structure which shown is completely different from the structure introduced, resulting with a=b=c= 3.84 Angstroms instead of being 5.43, and the angles alpha=beta=gamma= 60°, instead of being 90°. 
> 
> Does anyone know why it happens? Is it an internal bug?  
> 
> I attach also the output, saw you can see directly what happens.
> 
> Thanks in andvance,
> Tommaso Francese,
> Università Cà Foscari di Venezia.
> 
> <silicon.pw.out>
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