[Pw_forum] How to calculated about supercell of AFM structure?

[r95222066 at ntu.edu.tw]

Dear all,
     I encountered a problem about AFM supercell setting.In one unit  
cell,the magnetism calculation is fine. But I try many possibility to  
calculated the supercell, it didn't work very well.
Here is 1*1*1 uncell input file
---------------------------------------------------------------------------

  &control
     calculation='scf',
     restart_mode='from_scratch',
     pseudo_dir = './',
     outdir='./',
     prefix='SmOFeAs'
  /
  &system
     ibrav = 6,celldm(1)=7.626031,celldm(3)=2.1656
     nat= 8, ntyp= 5,nbnd=140,nspin=2,
     ecutwfc = 60.0,ecutrho=300,
     starting_magnetization(1)=0.0,
     starting_magnetization(2)=0.0,
     starting_magnetization(3)=-0.3,
     starting_magnetization(3)=0.3,
     starting_magnetization(4)=0.0,
     occupations='smearing', smearing='mp', degauss=0.005,
  /
  &electrons
     conv_thr = 1.0e-5,
     mixing_beta = 0.05,
  /

ATOMIC_SPECIES
  Sm  138.9055  Sm.pbe-nsp-van.UPF
   O  15.9994   O.pbe-van_ak.UPF
  Fe1 55.845    Fe.pbe-sp-van_ak.UPF
  Fe2 55.845    Fe.pbe-sp-van_ak.UPF
  As  74.92160  As.pbe-n-van.UPF
ATOMIC_POSITIONS (crystal)
Sm  0.25000000 0.25000000 0.14045310
Sm  0.75000000 0.75000000 0.85954689
  O  0.75000000 0.25000000 0.00000000
  O  0.25000000 0.75000000 0.00000000
Fe1 0.75000000 0.25000000 0.50000000
Fe2 0.25000000 0.75000000 0.50000000
As  0.25000000 0.25000000 0.63676752
As  0.75000000 0.75000000 0.36323247
K_POINTS (automatic)
12 12 6    0 0 0
-----------------------------------------------------------
Here is my 2*2*1 input file
  &control
     calculation='scf',
     restart_mode='from_scratch',
     pseudo_dir = './',
     outdir='./',
     prefix='SmOFeAs'
  /
  &system
     ibrav = 0,
     nat= 32, ntyp= 5,nbnd=320,nspin=2,
     ecutwfc = 60.0,ecutrho=300,
     starting_magnetization(1)=0.0,
     starting_magnetization(2)=0.0,
     starting_magnetization(3)=-0.3,
     starting_magnetization(3)=0.3,
     starting_magnetization(4)=0.0,
     occupations='smearing', smearing='mp', degauss=0.02,
  /
  &electrons
     conv_thr = 1.0e-4,
     mixing_beta = 0.05,
  /
CELL_PARAMETERS (simple tetragonal)
15.252062  0.000000   0.000000
  0.000000  15.252062  0.000000
  0.000000  0.000000  16.514932
ATOMIC_SPECIES
  Sm  138.9055  Sm.pbe-nsp-van.UPF
   O  15.9994   O.pbe-van_ak.UPF
  Fe1 55.845    Fe.pbe-sp-van_ak.UPF
  Fe2 55.845    Fe.pbe-sp-van_ak.UPF
  As  74.92160  As.pbe-n-van.UPF
ATOMIC_POSITIONS (angstrom)
La  1.00889  1.00889 1.22746
La  1.00889  5.0444  1.22746
La  5.04440  1.00889 1.22746
La  5.04440  5.04440 1.22746
La  3.02664  3.02664 7.51186
La  3.02664  7.06216 7.51886
La  7.06216  3.02664 7.51886
La  7.06216  7.06216 7.51886
  O  1.00889  3.02664 0.00000
  O  1.00889  7.06216 0.00000
  O  3.02664  1.00889 0.00000
  O  3.02664  5.04440 0.00000
  O  5.04440  3.02664 0.00000
  O  5.04440  7.06216 0.00000
  O  7.06216  1.00889 0.00000
  O  7.06216  5.04440 0.00000
Fe1  1.00889  3.02664 4.36966
Fe2  1.00889  7.06216 4.36966
Fe1  3.02664  1.00889 4.36966
Fe2  3.02664  5.04440 4.36966
Fe2  5.04440  3.02664 4.36966
Fe1  5.04440  7.06216 4.36966
Fe2  7.06216  1.00889 4.36966
Fe1  7.06216  5.04440 4.36966
As  3.02664  3.02664 3.17440
As  3.02664  7.06216 3.17440
As  7.06216  3.02664 3.17440
As  7.06216  7.06216 3.17440
As  1.00889  1.00889 5.56491
As  1.00889  5.04440 5.56491
As  5.04440  1.00889 5.56491
As  5.04440  5.04440 5.56491
K_POINTS (automatic)
10 10 6      0 0 0
----------------------------------------------------------------

Thanks a lot!
                 Bing-Hong Chen,National Taiwan University,Taiwan