[Pw_forum] DFT

[Ricardo Afonso]

Hi,

I have been seeking an optimized cell for my system lately. But I'm not
entirely sure whether my calculation goes right or not. I have used
crystal_sg to describe the atoms position. However, as it is known, my
output file shows me only de cell parameters and atomic positions and
crystal "units". My crystal is a "ferrite", whose symmetry is 227, which
should correpond to fcc. Why don't I have a fcc as my output on scf
calculations, for instace?

When do I know that my vc-relax calculation is right? I'm sending my input
file (on vc-relax) for any mistakes, in any case.

Best Regards.


Input file:

 &CONTROL
                 calculation = 'vc-relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = '/home/drumsris/Bulk-227/' ,
                  pseudo_dir = '/home/drumsris/Bulk-227/' ,
                      prefix = 'pwscf' ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                       lorbm = .false.,
          wf_collect = .false.,
                       nstep = 20 ,
 /
 &SYSTEM
                       ibrav = 2,
                   celldm(1) = 15.8370388,
          space_group = 227,
                         nat = 3,
                        ntyp = 3,
                     ecutwfc = 71 ,
                     ecutrho = 564 ,
               nosym = .true. ,
                   input_dft = 'pbe' ,
                 occupations = 'smearing' ,
                     degauss = 0.0002 ,
                    smearing = 'methfessel-paxton' ,
                       nspin = 2 ,
   starting_magnetization(1) = -1,
   starting_magnetization(2) = 1,
   starting_magnetization(3) = 0,
          !tot_magnetization = -1,
 /
 &ELECTRONS
            electron_maxstep = 100,
             diagonalization = 'david' ,
              diago_thr_init = 1.0e-5 ,
            conv_thr = 1.D-5 ,
         mixing_beta = 0.7,
         mixing_mode = 'plain'
 /
 &IONS
        ion_dynamics = 'bfgs' ,
       pot_extrapolation = 'atomic' ,
                 upscale = 10D0 ,
               bfgs_ndim = 1 ,
        trust_radius_max = 0.8D0 ,
        trust_radius_min = 1.D-3 ,
        trust_radius_ini = 0.5D0 ,
                     w_1 = 0.01D0 ,
                     w_2 = 0.5D0 ,
 /
 &CELL
           cell_dynamics = 'bfgs' ,
               press = 0.D0 ,
             cell_factor = 2.0 ,
          press_conv_thr = 0.5D0 ,
         cell_dofree = 'z' ,
/
ATOMIC_SPECIES
   Ni    58.69000  Ni.pbe-n-kjpaw_psl.1.0.0.UPF
   Fe    55.85000  Fe.pbe-spn-kjpaw_psl.1.0.0.UPF
    O    16.00000  O.pbe-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS crystal_sg
Fe    16d      0.62500    0.62500    0.62500 0 0 0
Ni    8a       0.00000    0.00000    0.00000 0 0 0
O     32e      0.37980    0.37980    0.37980
K_POINTS {automatic}
 5 5 5 0 0 0

-- 
Ricardo Afonso
Student of Magnetism and Superconductivity Group
Federal University of Sao Carlos
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