&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
      parm_file_name ../sample_pot/ethene_fake.pot
      parmtype CHM
      &CHARGE
        ATOM CE2
        CHARGE -0.42
      &END CHARGE
      &CHARGE
        ATOM HE2
        CHARGE 0.21
      &END CHARGE
    &END FORCEFIELD
    &POISSON
      &EWALD
        EWALD_TYPE spme
        ALPHA .44
        GMAX 24
        O_SPLINE 6
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &CELL
      ABC 24.955 24.955 24.955
    &END CELL
    &TOPOLOGY
      COORD_FILE_NAME ../sample_pdb/ethene.pdb
      COORDINATE pdb
    &END TOPOLOGY
    &COLVAR
      &TORSION
        ATOMS   3 1 2 4
      &END
    &END
    &COLVAR
      &TORSION
        ATOMS   3 1 2 6
      &END
    &END
    &COLVAR
      &TORSION
        ATOMS   5 1 2 4
      &END
    &END
    &COLVAR
      &TORSION
        ATOMS   5 1 2 6
      &END TORSION
    &END
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT ethene-restraint2
  RUN_TYPE md
&END GLOBAL
&MOTION
  &MD
    ENSEMBLE NVE
    STEPS 2
    TIMESTEP 0.5
    TEMPERATURE 298
  &END MD
  &CONSTRAINT
    &COLLECTIVE
      TARGET [deg] 0.0
      MOLECULE 1
      COLVAR 1
      &RESTRAINT
          K   [kcalmol] 4.90
      &END
    &END COLLECTIVE
    &COLLECTIVE
      TARGET [deg] 180.0
      MOLECULE 1
      COLVAR 2
      &RESTRAINT
          K   [kcalmol] 4.90
      &END
    &END COLLECTIVE
    &COLLECTIVE
      TARGET [deg] -180.0
      MOLECULE 1
      COLVAR 3
      &RESTRAINT
          K   [kcalmol] 4.90
      &END
    &END COLLECTIVE
    &COLLECTIVE
      TARGET [deg] 0.0
      MOLECULE 1
      COLVAR 4
      &RESTRAINT
          K   [kcalmol] 4.90
      &END
    &END COLLECTIVE
  &END CONSTRAINT
&END MOTION
