[Pw_forum] symmetry identification

[W. YU]

Dear PW users,

I met a problem when doing some calculation on a body
centered tetragonal structure. The space group no. is
139 (I4/mmm). There are all together 16 symmetry
operations, but pw can only identify 8 symmetry
operations without inversion. So in a follow up phonon
calculation, the given phonon symmetry modes are not
consistent with the space analysis. I an not sure
whether the lost symmetry operations are caused by the
input coordinates. I tried it with wie2k package, it
could identify all the symmetry operations. So what
could be the cause for this problem? The input file is
attached. Any help would be much appreciated. Thanks.

Wen Yu

 =====================================================
The following is my  input file:

 &system
    ibrav = 7, celldm(1) =7.1747,celldm(3)=3.2818,
    nat= 7, ntyp= 3,
    ecutwfc = 50.0,ecutrho = 400.0,
    occupations = 'smearing',
    smearing = 'methfessel-paxton', 
    degauss = 0.02,
  /
 &electrons
    mixing_beta = 0.2
 /
ATOMIC_SPECIES
 Sr  87.62  Sr.pbe-nsp-van.UPF
 Cu  63.55  Cu.pbe-n-van_ak.UPF
 O   16.0   O.pbe-van_ak.UPF
ATOMIC_POSITIONS bohr
 Sr 0.0 0.0  8.341471850
 Sr 0.0 0.0  15.20471415
 Cu 0.0 0.0  0.0
 O  0.000000 3.587363  0.0
 O  3.587363 0.000000  0.0
 O  0.0 0.0   3.64071128
 O  0.0 0.0  19.90547472
K_POINTS automatic
8 8 8 0 0 0
EOF
 


 
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