# Chapter 7, example 4: CELL_OPT of a layered crystal (bulk 2H-MoS2) with KEEP_ANGLES
# Target versions: CP2K 2023.1 ... 2026.2 (no TYPE line, no 2026.2-only keywords)
# a and c relax independently, the hexagonal angles (90, 90, 120) stay fixed.
# Start: a = 3.16 A, c = 13.00 A (exp. c = 12.29 A; c is deliberately too large)
# Run:  mpirun -np 32 cp2k.psmp -i layered_cell_opt_keep_angles.inp -o mos2_cellopt.out
@SET PROJ  mos2_cellopt
@SET A0    3.16
@SET C0    13.00

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

&FORCE_EVAL
  METHOD QUICKSTEP
  STRESS_TENSOR ANALYTICAL
  &DFT
    BASIS_SET_FILE_NAME BASIS_MOLOPT_UZH
    POTENTIAL_FILE_NAME POTENTIAL_UZH
    &MGRID
      CUTOFF 600
      REL_CUTOFF 60
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-12
    &END QS
    &KPOINTS
      SCHEME MONKHORST-PACK 9 9 2
    &END KPOINTS
    &SCF
      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-7
      MAX_SCF 150
      ADDED_MOS 10
      &DIAGONALIZATION
        ALGORITHM STANDARD
      &END DIAGONALIZATION
      &MIXING
        METHOD BROYDEN_MIXING
        ALPHA 0.2
        NBROYDEN 8
      &END MIXING
      ! small smearing only to stabilise the first SCF cycles of a semiconductor
      &SMEAR ON
        METHOD FERMI_DIRAC
        ELECTRONIC_TEMPERATURE [K] 100
      &END SMEAR
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
      ! interlayer binding is pure dispersion: without it c is far too large
      &VDW_POTENTIAL
        DISPERSION_FUNCTIONAL PAIR_POTENTIAL
        &PAIR_POTENTIAL
          TYPE DFTD3(BJ)
          PARAMETER_FILE_NAME dftd3.dat
          REFERENCE_FUNCTIONAL PBE
        &END PAIR_POTENTIAL
      &END VDW_POTENTIAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ! ABC + ALPHA_BETA_GAMMA puts A along x and B in the xy plane (required for CELL_OPT)
      ABC ${A0} ${A0} ${C0}
      ALPHA_BETA_GAMMA 90.0 90.0 120.0
    &END CELL
    &COORD
      SCALED
      Mo 0.333333 0.666667 0.250000
      Mo 0.666667 0.333333 0.750000
      S  0.333333 0.666667 0.621000
      S  0.666667 0.333333 0.121000
      S  0.666667 0.333333 0.379000
      S  0.333333 0.666667 0.879000
    &END COORD
    &KIND Mo
      BASIS_SET DZVP-MOLOPT-PBE-GTH-q14
      POTENTIAL GTH-PBE-q14
    &END KIND
    &KIND S
      BASIS_SET DZVP-MOLOPT-PBE-GTH-q6
      POTENTIAL GTH-PBE-q6
    &END KIND
  &END SUBSYS
&END FORCE_EVAL

&MOTION
  &CELL_OPT
    OPTIMIZER BFGS
    MAX_ITER 150
    EXTERNAL_PRESSURE [bar] 1.01325
    PRESSURE_TOLERANCE [bar] 50.0
    KEEP_ANGLES T
  &END CELL_OPT
  &PRINT
    &TRAJECTORY
      FORMAT XYZ
    &END TRAJECTORY
    &CELL ON
    &END CELL
    &RESTART
      BACKUP_COPIES 1
    &END RESTART
  &END PRINT
&END MOTION