[Pw_forum] Input ibrav not compatible with space group number

[Tsung-Lung Li]

Dear QE Friends:

I encounter a problem with the space_group option. A part of my QE input is
attached at the end of this message.

The crystal I am working on has symmetry "C 1 2/c 1" (as suggested by the
cif file from which I take the structure data).

Suggested by the following two webpages, I set "space_group = 15".
http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-wp-list?gnum=15&gua=b
http://img.chem.ucl.ac.uk/sgp/large/015ay1.htm

Because the unique axis is along b in my problem,
I take "ibrav = -12" (monoclinic).

Running QE, I got the following error message.

      Error in routine input (1):
      Input ibrav not compatible with space group number

There is not much information about space_group option in QE manual.
Could ould you please point out what is wrong with the input?

Thbak you.

Tsung-Lung Li

---------------------------------------------------
&system
   ibrav = -12
   celldm(1) = 11.86181088389489 ! bohr
   ntyp = 4
   nat = 7
   space_group = 15
   uniqueb = .true.
   origin_choice = 1
   ....
/

ATOMIC_SPECIES
    Ca   40.0780000000  Ca_pbe_v1.uspp.F.UPF
     S   32.0650000000  S_pbe_v1.2.uspp.F.UPF
     O   15.9994000000  O.pbe-n-kjpaw_psl.0.1.UPF
     H    1.0079000000  H.pbe-rrkjus_psl.0.1.UPF

ATOMIC_POSITIONS crystal_sg
   Ca  0.00000   0.17050   0.25000
   S   0.00000   0.32727   0.75000
   O   0.08319   0.27218   0.59103
   O   0.19997   0.38195   0.91298
   O  -0.20823   0.06826  -0.07831
   H  -0.25800   0.08700  -0.23400
   H  -0.24400   0.02000  -0.07700

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