! E12 step 1: the ground state that hp.x will perturb.
! Same FeO AFM-II cell as E10, with two changes:
!   - conv_thr tightened to 1e-12 (linear response is noise-sensitive)
!   - a HUBBARD card with a negligible U (1e-8), whose only job is to tell
!     hp.x WHICH atoms and manifolds to perturb.

&CONTROL
  calculation = 'scf'
  prefix      = 'FeO'
  outdir      = './tmp/'
  pseudo_dir  = './pseudo/'
  verbosity   = 'high'
  tprnfor     = .true.
  tstress     = .true.
/
&SYSTEM
  ibrav       = 0
  celldm(1)   = 8.18          ! bohr (= 4.33 Angstrom)
  nat         = 4
  ntyp        = 3
  ecutwfc     = 70
  ecutrho     = 700
  occupations = 'smearing'
  smearing    = 'mv'
  degauss     = 0.01
  nspin       = 2
  starting_magnetization(1) =  0.6
  starting_magnetization(2) = -0.6
  starting_magnetization(3) =  0.0
/
&ELECTRONS
  conv_thr         = 1.0d-12    ! very tight: the response matrix inherits this quality
  mixing_beta      = 0.2
  mixing_mode      = 'local-TF'
  electron_maxstep = 300
/

ATOMIC_SPECIES
  Fe1  55.845  Fe.pbe-spn-kjpaw_psl.1.0.0.UPF
  Fe2  55.845  Fe.pbe-spn-kjpaw_psl.1.0.0.UPF
  O    15.999  O.pbe-n-kjpaw_psl.1.0.0.UPF

CELL_PARAMETERS (alat)
  0.5  0.5  1.0
  0.5  1.0  0.5
  1.0  0.5  0.5

ATOMIC_POSITIONS (crystal)
  Fe1  0.00  0.00  0.00
  Fe2  0.50  0.50  0.50
  O    0.25  0.25  0.25
  O    0.75  0.75  0.75

K_POINTS (automatic)
  6 6 6  0 0 0

! effectively-zero U: registers the Fe-3d manifolds with hp.x without
! biasing the ground state
HUBBARD (ortho-atomic)
U Fe1-3d 1.0d-8
U Fe2-3d 1.0d-8