# Chapter 8, example 2: O2 molecule, spin-polarized (UKS) geometry optimization
# Target versions: CP2K 2023.1 ... 2026.2
# Ground state of O2 is the triplet X 3Sigma_g-.  Compare with MULT 1 (closed-shell
# UKS solution, NOT the a 1Delta_g state) by changing the @SET line below.
@SET MULT 3
@SET PROJ o2_mult${MULT}

&GLOBAL
  PROJECT ${PROJ}
  RUN_TYPE GEO_OPT
  PRINT_LEVEL MEDIUM
&END GLOBAL

&FORCE_EVAL
  METHOD QUICKSTEP
  &DFT
    BASIS_SET_FILE_NAME BASIS_MOLOPT_UZH
    POTENTIAL_FILE_NAME POTENTIAL_UZH
    ! spin-unrestricted Kohn-Sham (aliases: LSD, SPIN_POLARIZED)
    UKS
    CHARGE 0
    ! 2S+1: 3 = triplet (two unpaired electrons)
    MULTIPLICITY ${MULT}
    &MGRID
      CUTOFF 400
      REL_CUTOFF 60
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-12
      EXTRAPOLATION ASPC
    &END QS
    &POISSON
      PERIODIC NONE
      POISSON_SOLVER MT
    &END POISSON
    &SCF
      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-7
      MAX_SCF 40
      &OT
        MINIMIZER DIIS
        PRECONDITIONER FULL_ALL
      &END OT
      &OUTER_SCF
        EPS_SCF 1.0E-7
        MAX_SCF 10
      &END OUTER_SCF
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ABC 12.0 12.0 12.0
      PERIODIC NONE
    &END CELL
    &COORD
      O 0.000 0.000  0.625
      O 0.000 0.000 -0.625
    &END COORD
    &TOPOLOGY
      &CENTER_COORDINATES
      &END CENTER_COORDINATES
    &END TOPOLOGY
    &KIND O
      BASIS_SET TZVP-MOLOPT-PBE-GTH-q6
      POTENTIAL GTH-PBE-q6
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

&MOTION
  &GEO_OPT
    OPTIMIZER BFGS
    MAX_ITER 100
    MAX_FORCE 1.0E-4
  &END GEO_OPT
&END MOTION