[QE-users] No symmetry found

Oleksandr Motornyi oleksandr.motornyi at polytechnique.edu
Mon Jun 3 11:13:05 CEST 2019


Dear Willem

It is likely due to the fact that the slab in your supercell is not 
centered, i.e. your atoms coordinate along z axis spans from 1.14 to 
12.54. I believe that if you want the code fo find inversion symmetry 
correctly you need it to be symmetrical with respect to z=0, i.e. it 
should span form h/2 to -h/2.

P.S. Also it is better to avoid using ibrav=0 and Cell params and use 
the ibrav value. I would recommend you to try and generate the slab 
using gener_3d_slab.x code of thermo_pw module 
(https://dalcorso.github.io/thermo_pw/)

Best regards,

Oleksandr

On 03/06/2019 11:01, Offermans Willem wrote:
> Dear QE friends,
>
> I’m calculating stepped Pd surfaces (Pd533).
>
> My palladium slab model has an inversion center. I define one half of 
> the atoms and generate the other half by using the inversion center.
>
> The input and only part of the output file is given below.
>
> pw.x program is not able to detect and to use the symmetry (inversion 
> center).
>
> At first, I thought I made a mistake in the definition. Running abinit 
> with the same model showed me that the symmetry could be detected
> and that the definition of the atomic positions is fine.
>
> Why can't QE detect and use the symmetry?
>
>
> <snip>
> &CONTROL
>    verbosity        = 'high'
>    tprnfor          = .true.
>    pseudo_dir       = './'
> /
> &SYSTEM
>    ecutwfc          = 35
>    ecutrho          = 140
>    occupations      = 'smearing'
>    degauss          = 1e-05
>    ntyp             = 1
>    nat              = 38
>    ibrav            = 0
> /
> &ELECTRONS
>    electron_maxstep = 200
>    conv_thr         = 0.0001
>    mixing_beta      = 0.3
> /
> &IONS
> /
> &CELL
> /
>
> ATOMIC_SPECIES
> Pd 106.42 Pd.pbe-n-kjpaw_psl.0.2.2.UPF
>
> K_POINTS automatic
> 2 3 1  0 0 0
>
> CELL_PARAMETERS angstrom
> 5.58600000000000 0.00000000000000 0.00000000000000
> 4.18950000000000 8.86896616015644 -2.28047495053114
> 0.00000000000000 0.00000000000000 18.24379960424911
>
> ATOMIC_POSITIONS angstrom
> Pd 4.1896396500 8.8680792635 1.1404655228
> Pd 2.7930000000 0.0000000000 3.4207124258
> Pd 1.3965000000 2.4188089528 3.4207124258
> Pd 4.1895000000 2.4188089528 3.4207124258
> Pd 2.7930000000 4.8376179055 3.4207124258
> Pd 5.5860000000 4.8376179055 3.4207124258
> Pd 4.1895000000 7.2564268583 3.4207124258
> Pd 6.9825000000 7.2564268583 3.4207124258
> Pd 1.3965000000 0.8062696509 5.7011873763
> Pd 4.1895000000 0.8062696509 5.7011873763
> Pd 2.7930000000 3.2250786037 5.7011873763
> Pd 5.5860000000 3.2250786037 5.7011873763
> Pd 4.1895000000 5.6438875565 5.7011873763
> Pd 6.9825000000 5.6438875565 5.7011873763
> Pd 5.5860000000 8.0626965092 5.7011873763
> Pd 8.3790000000 8.0626965092 5.7011873763
> Pd 2.7930000000 1.6125393018 7.9816623269
> Pd 5.5860000000 1.6125393018 7.9816623269
> Pd 4.1895000000 4.0313482546 7.9816623269
> Pd 6.9825000000 4.0313482546 7.9816623269
> Pd 5.5860000000 6.4501572074 7.9816623269
> Pd 8.3790000000 6.4501572074 7.9816623269
> Pd 2.7930000000 0.0000000000 10.2621372774
> Pd -0.0000000000 0.0000000000 10.2621372774
> Pd 4.1895000000 2.4188089528 10.2621372774
> Pd 1.3965000000 2.4188089528 10.2621372774
> Pd 5.5860000000 4.8376179055 10.2621372774
> Pd 2.7930000000 4.8376179055 10.2621372774
> Pd 6.9825000000 7.2564268583 10.2621372774
> Pd 4.1895000000 7.2564268583 10.2621372774
> Pd 4.1895000000 0.8062696509 12.5426122279
> Pd 1.3965000000 0.8062696509 12.5426122279
> Pd 5.5860000000 3.2250786037 12.5426122279
> Pd 2.7930000000 3.2250786037 12.5426122279
> Pd 6.9825000000 5.6438875565 12.5426122279
> Pd 4.1895000000 5.6438875565 12.5426122279
> Pd 8.3790000000 8.0626965092 12.5426122279
> Pd 5.5858603500 8.0635834058 12.5423841804
>
> </snip>
>
> Part of the output:
>
> <snip>
>      Program PWSCF v.6.2.2 starts on  3Jun2019 at 10:44:39
>
>      This program is part of the open-source Quantum ESPRESSO suite
>      for quantum simulation of materials; please cite
>          "P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);
>          "P. Giannozzi et al., J. Phys.:Condens. Matter 29 465901 (2017);
>           URL http://www.quantum-espresso.org",
>      in publications or presentations arising from this work. More 
> details at
> http://www.quantum-espresso.org/quote
>
>      Serial version
>> ...
>
>      No symmetry found
>
>
>                                     s            frac. trans.
>
>       isym =  1     identity
>
>  cryst.   s( 1) = (     1          0          0    )
>                   (     0          1          0    )
>                   (     0          0          1    )
>
>  cart.    s( 1) = (  1.0000000  0.0000000  0.0000000 )
>                   (  0.0000000  1.0000000  0.0000000 )
>                   (  0.0000000  0.0000000  1.0000000 )
>
>> ...
> </snip>
>
>
>
> Met vriendelijke groeten,
> Mit freundlichen Grüßen,
> With kind regards,
>
>
> Willem Offermans
> Researcher Electrocatalysis SCT
> VITO NV | Boeretang 200 | 2400 Mol
> Phone:+32(0)14335263 Mobile:+32(0)492182073
>
> Willem.Offermans at Vito.be <mailto:Willem.Offermans at Vito.be>
>
>
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-- 
Oleksandr Motornyi
PhD candidate

Laboratoire de Solides Irradies
Ecole Polytechnique (Palaiseau, France)

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