[Pw_forum] Problem about "ibrav=7" running scf calculation

[潘登]

Dear All,

 I have a problem while running the scf calculation with the option "ibrav=7".
Here is the error information:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    from  read_namelists  : error #        19
     reading namelist electrons
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    stopping ...

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    from  read_namelists  : error #        19
     reading namelist electrons
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    stopping ...

And my input file is :

&control
    calculation = 'scf'
    restart_mode='from_scratch'
    prefix='BaNiAs',
    pseudo_dir = '/mywork'
/
&system
    ibrav=  7 , celldm(1) = 7.7702 , celldm(3) = 2.806, nat=  10, ntyp=  3,
    ecutwfc =18.0
/
&electrons
    mixing_beta = 0.7
    conv_thr =  1.0d-8
ATOMIC_SPECIES
Ba Ba.pw91-nsp-van.UPF
Ni NiUS.RRKJ3.UPF
As As.gon.UPF

ATOMIC_POSITIONS
Ba 0.0000 0.0000  0.0000
Ni 0.5000 0.0000  0.2500
Ni 0.0000 0.5000  0.2500
As 0.0000 0.0000  0.3476
As 0.0000 0.0000 -0.3476

K_POINTS (automatic)

2 2 2 0 0 0

I have tried to remove the option 'celldm(1) = 7.7702', at this time
the error information gives:
from  iosys  : error #         1
      invalid lattice parameters ( celldm or a )

If it helps.I was trying to calculation the Dos of BaNiAs,which  have
symmetry of the space group I4_mmm,with the lattice parameter a=7.7702
c=21.81 (bohr).

Please tell me the proper option sets, or point in out where I was wrong.

Thanks

Pan Deng
Nanjing University