! E02: the same crystal as E01, written with an explicit cell.
! ibrav=0 + CELL_PARAMETERS + fractional coordinates is exactly what
! structure generators (ASE, pymatgen) emit, so learn to read it.

&CONTROL
  calculation = 'scf'
  prefix      = 'si_ibrav0'   ! separate prefix so E01's files are untouched
  outdir      = './tmp/'
  pseudo_dir  = './pseudo/'
  verbosity   = 'high'
/
&SYSTEM
  ibrav       = 0             ! cell given explicitly below
  nat         = 2
  ntyp        = 1
  ecutwfc     = 30            ! identical basis settings to E01,
  ecutrho     = 240           ! so the energies are directly comparable
  occupations = 'fixed'
/
&ELECTRONS
  conv_thr    = 1.0d-8
/

ATOMIC_SPECIES
  Si  28.0855  Si.pbe-n-kjpaw_psl.1.0.0.UPF

! the three fcc primitive vectors as rows, in Angstrom.
! 2.715 = a/2 with a = 5.430 A; note E01's celldm(1)=10.26 bohr is 5.4293 A,
! so the two inputs differ in the 4th digit of a (visible in the energy).
CELL_PARAMETERS (angstrom)
  -2.715   0.000   2.715
   0.000   2.715   2.715
  -2.715   2.715   0.000

! fractional ('crystal') coordinates: independent of the cell size,
! the safest choice in practice
ATOMIC_POSITIONS (crystal)
  Si  0.00  0.00  0.00
  Si  0.25  0.25  0.25

K_POINTS (automatic)
  8 8 8  0 0 0