&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
      parm_file_name ../sample_pot/NaCl_wat.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 spme
        GMAX 25
        ALPHA .44
        NS_MAX 50
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &CELL
      ABC 28.912 29.461 29.496
    &END CELL
    &TOPOLOGY
      COORD_FILE_NAME ../sample_pdb/NaCl_wat.pdb
      COORDINATE pdb
      CONN_FILE_NAME  ../sample_psf/NaCl_wat.psf
      CONNECTIVITY PSF
    &END TOPOLOGY
    &COLVAR
      &DISTANCE
        ATOMS 1 2
      &END
    &END
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT NaCl_fe
  RUN_TYPE MD
&END GLOBAL
&MOTION
  &CONSTRAINT
    &G3X3
      DISTANCES 1.8897268 1.8897268 3.0859239
      MOLECULE 3
      ATOMS 1 2 3
    &END G3X3
    &COLLECTIVE
      COLVAR 1
      INTERMOLECULAR
      &RESTRAINT
        K 0.05
      &END
    &END
  &END CONSTRAINT
  &MD
    ENSEMBLE NVE
    STEPS 10
    TIMESTEP 1.0
    TEMPERATURE 298
  &END MD
  &FREE_ENERGY
    METHOD UI
    &UMBRELLA_INTEGRATION
     &CONVERGENCE_CONTROL
        EPS_CONV 0.5
        COARSE_GRAINED_WIDTH     3
        MAX_COARSE_GRAINED_WIDTH 3
        COARSE_GRAINED_POINTS    2
     &END
     &UVAR
       COLVAR 1
     &END
    &END
  &END
&END MOTION
