[Pw_forum] Get wrong symmtry

[yumin qian]

Dear Prof.

 I am doing LaOFeAs ground state calculation , it symmetry blongs to
  p4/nmm space group , when I finish the ground state calculation , I
procced to do the phonon calculation of Gamma point , But the output file
tell me that at Gamma point the symmetry is C_4v , but it should be D_4h,
then I look at the x.save fold to find the data-file.xml  I find the
symmetry operation is completely different from the D_4h , I also use the
Vasp to do the calculation and I get the D_4h symmetry operation , I check
the possible error of my in put file for SCF calculation the only possible
error is the parameter ibrav=6, and the crystal is indeed a
Tetragonal P (st)  cell
   where is the errror ? Or what mistake I have made , is there someone to
tell me what's the problem ? Thanks ,I am looking forward to the answer.


this is my input file for ground state SCF calculation


 &control
    calculation='scf'
    restart_mode='from_scratch',
    pseudo_dir = '~/software/espresso-4test/pseudo',
    outdir='./outscf'
    prefix='LaOFeAs',
    wf_collect=.true.
    tstress = .true.
    tprnfor = .true.
 /
 &system
    ibrav = 6, celldm(1) =7.633740 , celldm(3)=2.136,
    , nat= 8, ntyp= 4,
    ecutwfc = 30.0, ecutrho = 250.0
    occupations='smearing', smearing='gaussian', degauss=0.02,
 /
 &electrons
    diagonalization='david'
    conv_thr = 1.0e-10
    mixing_beta = 0.5
 /
ATOMIC_SPECIES
La  138.9 La.pbe-nsp-van.UPF
O   16.00 O.pbe-rrkjus.UPF
Fe  55.85 Fe.pbe-sp-van.UPF
As  74.92 As.pbe-n-van.UPF
ATOMIC_POSITIONS
La    0.2500000000    0.2500000000    0.1461000000
La    0.7500000000    0.7500000000    0.8539000000
O     0.7500000000    0.2500000000    0.0000000000
O     0.2500000000    0.7500000000    0.0000000000
Fe    0.7500000000    0.2500000000    0.5000000000
Fe    0.2500000000    0.7500000000    0.5000000000
As    0.2500000000    0.2500000000    0.6369000000
As    0.7500000000    0.7500000000    0.3631000000
K_POINTS (automatic)
 8 8 4 0 0 0
~

-- 
Sincerely Y. M. Qian
Lab.of Condensed Matter Theory and Materials Computation
Institute of Physics
Chinese Academy of Sciences
Tel:  + 8610 8264 9147
E-Mail:yuminqian at gmail.com <E-Mail%3Ayuminqian at gmail.com>
P.O.Box 603   Beijing 100190
China
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.democritos.it/pipermail/pw_forum/attachments/20081109/a7bcfbba/attachment.htm