# https://doi.org/10.1557/opl.2012.520
# https://doi.org/10.1103/PhysRevB.85.184103

# UO2 fluorite structure (#225)
@SET system   UO2

# Relax atoms and cell
@SET run_type cell_opt

# Select force field parameter file
@SET ff       Morelon
@SET ffp_file ${ff}.ffp

# Use 5x5x5 unit cells
@SET na       5
@SET nb       ${na}
@SET nc       ${na}

@SET project  ${system}-${run_type}-${na}x${nb}x${nc}-${ff}

# Experimental lattice constant
@SET a        5.4682
@SET b        ${a}
@SET c        ${a}

# Set grid size for SPME (approx. 2 points per Angstrom)
@SET ngpa     12*${na}
@SET ngpb     ${ngpa}
@SET ngpc     ${ngpa}

# Control print frequency
@SET PF       1

&GLOBAL
 PREFERRED_DIAG_LIBRARY ScaLAPACK
 PRINT_LEVEL low # medium
 PROJECT_NAME ${project}
 RUN_TYPE ${run_type}
&END GLOBAL

# Uncomment to restart a run
#&EXT_RESTART
# RESTART_FILE_NAME ${project}-1.restart
#&END EXT_RESTART

&MOTION
 &CELL_OPT
  EXTERNAL_PRESSURE [bar] 1.0
  KEEP_ANGLES no
  MAX_DR 0.001
  MAX_FORCE 0.0001
  MAX_ITER 200
  OPTIMIZER LBFGS # CG
  PRESSURE_TOLERANCE [bar] 2.0
  RMS_DR 0.0003
  RMS_FORCE 0.00003
  TYPE direct_cell_opt
  &CG
   &LINE_SEARCH
    TYPE 2PNT
   &END LINE_SEARCH
  &END CG
  &LBFGS
   TRUST_RADIUS 0.1
  &END LBFGS
 &END CELL_OPT
 &PRINT
  &CELL on
   &EACH
    MD ${PF}
   &END EACH
  &END CELL
  &STRESS on
   &EACH
    MD ${PF}
   &END EACH
  &END STRESS
  &RESTART on
   ADD_LAST NUMERIC
   BACKUP_COPIES 0
   &EACH
    MD ${PF}
   &END EACH
  &END RESTART
  &RESTART_HISTORY off
  &END RESTART_HISTORY
  &STRUCTURE_DATA on
   DISTANCE 1 5
  &END STRUCTURE_DATA
  &TRAJECTORY on
   FORMAT xyz
   &EACH
    MD ${PF}
   &END EACH
  &END TRAJECTORY
 &END PRINT
&END MOTION

&FORCE_EVAL
 METHOD Fist
 STRESS_TENSOR analytical
 &MM
  @INCLUDE ${ffp_file}
  &POISSON
   &EWALD
    EWALD_TYPE spme
    ALPHA [angstrom^-1] 0.35
    GMAX ${ngpa} ${ngpb} ${ngpc}
   &END EWALD
  &END POISSON
  &PRINT
   &FF_INFO off
    SPLINE_DATA
    SPLINE_INFO
   &END FF_INFO
  &END PRINT
 &END MM
 &SUBSYS
  &CELL
   ABC ${a} ${b} ${c}
   MULTIPLE_UNIT_CELL ${na} ${nb} ${nc}
  &END CELL
  &COORD
   SCALED
   U        0     0     0  UO2  1
   U        0   1/2   1/2  UO2  1
   U      1/2     0   1/2  UO2  1
   U      1/2   1/2     0  UO2  1
   O      1/4   1/4   1/4  UO2  1
   O      3/4   1/4   1/4  UO2  1
   O      1/4   3/4   1/4  UO2  1
   O      3/4   3/4   1/4  UO2  1
   O      1/4   1/4   3/4  UO2  1
   O      3/4   1/4   3/4  UO2  1
   O      1/4   3/4   3/4  UO2  1
   O      3/4   3/4   3/4  UO2  1
  &END COORD
  &TOPOLOGY
   CONNECTIVITY user
   DISABLE_EXCLUSION_LISTS
   MULTIPLE_UNIT_CELL ${na} ${nb} ${nc}
   PARA_RES off
  &END TOPOLOGY
 &END SUBSYS
&END FORCE_EVAL