&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
      &spline
       rcut_nb 6.9
      &end
      parm_file_name ../sample_pot/charmm.pot
      parmtype CHM
      &CHARGE
        ATOM NH3
        CHARGE -1.14
      &END CHARGE
      &CHARGE
        ATOM HC
        CHARGE 0.38
      &END CHARGE
    &END FORCEFIELD
    &POISSON
      &EWALD
        EWALD_TYPE ewald
        ALPHA .5
        GMAX 21
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &CELL
      ABC 13.858 13.858 13.858
    &END CELL
    &TOPOLOGY
      COORD_FILE_NAME ../sample_pdb/NH3_1.pdb
      COORDINATE PDB
    &END TOPOLOGY
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT nh3-restraint-fixd-2
  PRINT_LEVEL LOW
  RUN_TYPE GEO_OPT
&END GLOBAL
&MOTION
  &CONSTRAINT
    &FIXED_ATOMS
      LIST 2 3 4
      #&RESTRAINT
      #    K   [kcalmol*angstrom^-2]  100.0
      #&END
    &END FIXED_ATOMS
  &END CONSTRAINT
  &GEO_OPT
    OPTIMIZER BFGS
    MAX_ITER 50
  &END
&END MOTION
