&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
      parm_file_name ../sample_pot/water.pot
      parmtype CHM
      &CHARGE
        ATOM OT
        CHARGE -0.8476
      &END CHARGE
      &CHARGE
        ATOM HT
        CHARGE 0.4238
      &END CHARGE
    &END FORCEFIELD
    &POISSON
      &EWALD
        EWALD_TYPE pme
        ALPHA .44
        NS_MAX 25
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &COORD
OT     -0.757  -5.616  -7.101    WAT1
HT     -1.206  -5.714  -6.262    WAT1
HT      0.024  -5.102  -6.896    WAT1
OT    -11.317  -2.629  -9.689    WAT2
HT    -11.021  -3.080 -10.480    WAT2
HT    -10.511  -2.355  -9.252    WAT2
    &END
    &CELL
      ABC 24.955 24.955 24.955
    &END CELL
    &COLVAR
      &DISTANCE
        ATOMS 1 2
      &END DISTANCE
    &END COLVAR
    &COLVAR
      &DISTANCE
        ATOMS 1 3
      &END DISTANCE
    &END COLVAR
    &COLVAR
      &DISTANCE
        ATOMS 2 3
      &END DISTANCE
    &END COLVAR
    &TOPOLOGY
    &END TOPOLOGY
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT water_3_dist_2_restr
  RUN_TYPE MD
&END GLOBAL
&MOTION
  &CONSTRAINT
    &COLLECTIVE
      MOLNAME WAT2
      COLVAR 1
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
    &COLLECTIVE
      MOLNAME WAT2
      COLVAR 2
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
    &COLLECTIVE
      MOLNAME WAT2
      COLVAR 3
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
    &COLLECTIVE
      MOLNAME WAT1
      COLVAR 1
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
    &COLLECTIVE
      MOLNAME WAT1
      COLVAR 2
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
    &COLLECTIVE
      MOLNAME WAT1
      COLVAR 3
      &RESTRAINT
          K   [kcalmol*angstrom^-2] 450.0
      &END
    &END COLLECTIVE
  &END CONSTRAINT
  &MD
    ENSEMBLE NVE
    STEPS 10
    TIMESTEP 1.0
    TEMPERATURE 298
  &END MD
&END MOTION
