&GLOBAL
  PROJECT_NAME MgO
  RUN_TYPE GEO_OPT
  PRINT_LEVEL LOW
  FLUSH_SHOULD_FLUSH .TRUE.
&END GLOBAL

&MOTION
  &GEO_OPT
    TYPE MINIMIZATION
    OPTIMIZER BFGS
    MAX_ITER 200
  &END GEO_OPT
&END MOTION

&FORCE_EVAL
  METHOD QS
  STRESS_TENSOR ANALYTICAL

  &DFT
    ! in the geometry optimization there is no need to run an all-electron calculation, so we are 
    ! going to make use of the GTH pseudopotentials for the core electrons.
    BASIS_SET_FILE_NAME  GTH_BASIS_SETS  
    POTENTIAL_FILE_NAME  GTH_POTENTIALS
    
    &MGRID
      NGRIDS 5
      CUTOFF 400
      REL_CUTOFF 60
    &END MGRID

    &QS
      METHOD GPW ! to optimize the geometry the GPW method will be used
    &END QS

    &SCF
      MAX_SCF 200
      EPS_SCF 1.0E-6
      SCF_GUESS ATOMIC

      &OT
        MINIMIZER DIIS
        PRECONDITIONER FULL_ALL
      &END OT
    &END SCF

    &XC
      &XC_FUNCTIONAL PBE  ! PBE exchange-correlation functional
      &END XC_FUNCTIONAL

      &XC_GRID
         XC_SMOOTH_RHO NN50
         XC_DERIV NN50_SMOOTH
      &END XC_GRID
   &END XC
  &END DFT

  &SUBSYS
    &COORD
      O     3.010000   1.737824   1.228827
      Mg    0.000000   0.000000   0.000000
    &END COORD

    &CELL
      PERIODIC XYZ  ! we are considering the system periodic in the three directions 
      ALPHA_BETA_GAMMA 60 60 60
      ABC 3.010 3.010 3.010
    &END CELL

    &KIND Mg
      ELEMENT Mg
      BASIS_SET DZVP-GTH    
      POTENTIAL GTH-PBE-q10 
    &END KIND

    &KIND O
      ELEMENT O
      BASIS_SET DZVP-GTH
      POTENTIAL GTH-PBE-q6
    &END KIND
  &END SUBSYS
&END FORCE_EVAL