[Pw_forum] Construction of PtH structure, wrong pointgroup problem

[Bahadir Altintas]

c should be 4.749 instead of 7.769. i wrote wrong literature value. so 
ignore the previous c value in the mail.

bahadir

On 05/22/2012 02:54 PM, Bahadir Altintas wrote:
> Hi,
> I have a problem in constructing the PtH structure.
> I have prepared the input with following data from J. Phys. Chem. C, 
> 2012, 116 (2), pp 1995--2000 
> (http://http://pubs.acs.org/doi/abs/10.1021%2Fjp210780m) for hexagonal 
> PtH.
>
> Spacegroup : 194 - P63/mmc
> Point group : D_6h
> a=2.795
> c=7.769
     Pt: 2c (1/3 2/3 0.25)
> H: 2a ( 0 0 0 )
>
> Point group of this input  gives  D_3d (-3m) instead of D_6h (6/mmm). 
> I am not sure what am i missing.
>
> here is my input for vc-relax under 100GPa (Espresso-4.3.2):
>
> &CONTROL
>     calculation =   "vc-relax"   ,
>     restart_mode = 'from_scratch' ,
>     outdir='/tmp' ,
>     pseudo_dir ='/home/pseudos/espresso/' ,
>     etot_conv_thr = 1.0D-14  ,
>     forc_conv_thr = 1.0D-5 ,
>     prefix='PtH_sp194_100GPa.opt',
>     tstress=.true.,
>  verbosity='high'
>   /
> &SYSTEM
>      ibrav= 4,
>      celldm(1)=5.2817842823,
>      celldm(3)=1.706261153,
>      nat= 4,
>      ntyp= 2,
>                      ecutwfc=37
>                   ecutrho  =  222 ,
>                   occupations  =  'smearing' ,
>                      smearing  =  'mp' ,
>                       degauss  =  0.02 ,
>  /
> &ELECTRONS
>    conv_thr  =  1.0d-7,
>   diagonalization='david'
>   /
> &IONS
>   ion_dynamics = 'bfgs',
>   /
> &CELL
>     cell_dynamics = 'bfgs' ,
>     cell_factor=1.2,
>      press= 1000.00
>   /
>
>  ATOMIC_SPECIES
>  Pt  195.08 Pt.pbe-n-van.UPF
>  H  1.00794 H.pbe-van_ak.UPF
>
>  ATOMIC_POSITIONS (crystal)
>  Pt       0.333333343   0.666666687   0.250000438
>  Pt       0.666666627   0.333333313   0.749999562
>  H        0.000000000   0.000000000   0.000000000
>  H        0.000000000   0.000000000   0.500000000
>
>  K_POINTS automatic
>  4 4 4 1 1 1
>
>
>
>
>
> Thanks,
>
> Bahadir Altintas
> University at Buffalo
> Dept of Chemistry
>
>
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