&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
#####################################################
      &BOND
        #CTL2  HAL2  309.00      1.111
        ATOMS   CTL2 HAL2
        KIND    CHARMM
        K       [kcalmol*angstrom^-2] 309.0
        R0      [angstrom] 1.111
      &END BOND
      &BOND
        #CTL3  HAL3  322.00      1.111
        ATOMS   CTL3 HAL3
        KIND    CHARMM
        K       [kcalmol*angstrom^-2] 322.0
        R0      [angstrom] 1.111
      &END BOND
      &BOND
        #CTL2  CTL2  222.500     1.530
        ATOMS   CTL2 CTL2
        KIND    CHARMM
        K       [kcalmol*angstrom^-2] 222.5
        R0      [angstrom] 1.530
      &END BOND
      &BOND
        #CTL2  CTL3  222.500     1.528
        ATOMS   CTL2 CTL3
        KIND    CHARMM
        K       [kcalmol*angstrom^-2] 222.5
        R0      [angstrom] 1.528
      &END BOND
#####################################################
      &BEND
        #HAL2 CTL2 HAL2   35.500    109.00
        ATOMS   HAL2 CTL2 HAL2
        K       [kcalmol*rad^-2] 35.500
        THETA0  [deg] 109.00
      &END BEND
      &BEND
        #HAL3 CTL3 HAL3   35.500    108.40
        ATOMS   HAL3 CTL3 HAL3
        K       [kcalmol*rad^-2] 35.500
        THETA0  [deg] 108.40
      &END BEND
      &BEND
        #HAL2 CTL2 CTL3   34.600    110.10
        ATOMS   HAL2 CTL2 CTL3
        K       [kcalmol*rad^-2] 34.600
        THETA0  [deg] 110.10
      &END BEND
      &BEND
        #CTL2 CTL2 CTL3   58.000    115.00
        ATOMS   CTL2 CTL2 CTL3
        K       [kcalmol*rad^-2] 58.000
        THETA0  [deg] 115.00
      &END BEND
      &BEND
        #HAL3 CTL3 CTL2   34.600    110.10
        ATOMS   HAL3 CTL3 CTL2
        K       [kcalmol*rad^-2] 34.600
        THETA0  [deg] 110.10
      &END BEND
      &BEND
        #HAL2 CTL2 CTL2   26.500    110.10
        ATOMS   HAL2 CTL2 CTL2
        K       [kcalmol*rad^-2] 26.500
        THETA0  [deg] 110.10
      &END BEND
#####################################################
      &TORSION
        #CTL3 CTL2 CTL2 CTL3     0.10    2   180.00
        ATOMS   CTL3 CTL2 CTL2 CTL3
        K       [kcalmol] 0.10
        PHI0    [deg] 180.00
        M         2
      &END TORSION
      &TORSION
        #CTL3 CTL2 CTL2 CTL3     0.15    4     0.00
        ATOMS   CTL3 CTL2 CTL2 CTL3
        K       [kcalmol] 0.15
        PHI0    [deg] 0.00
        M         4
      &END TORSION
      &TORSION
        #CTL3 CTL2 CTL2 CTL3     0.10    6   180.00
        ATOMS   CTL3 CTL2 CTL2 CTL3
        K       [kcalmol] 0.10
        PHI0    [deg] 180.00
        M         6
      &END TORSION
      &TORSION
        #HAL2 CTL2 CTL3 HAL3     0.1600  3     0.00
        ATOMS   HAL2 CTL2 CTL3 HAL3
        K       [kcalmol] 0.16
        PHI0    [deg] 0.00
        M         3
      &END TORSION
      &TORSION
        #CTL2 CTL2 CTL3 HAL3     0.1600  3     0.00
        ATOMS   CTL2 CTL2 CTL3 HAL3
        K       [kcalmol] 0.16
        PHI0    [deg] 0.00
        M         3
      &END TORSION
      &TORSION
        #CTL3 CTL2 CTL2 HAL2     0.1900  3     0.00
        ATOMS   CTL3 CTL2 CTL2 HAL2
        K       [kcalmol] 0.19
        PHI0    [deg] 0.00
        M         3
      &END TORSION
      &TORSION
        #HAL2 CTL2 CTL2 HAL2     0.1900  3     0.00
        ATOMS   HAL2 CTL2 CTL2 HAL2
        K       [kcalmol] 0.19
        PHI0    [deg] 0.00
        M         3
      &END TORSION
#####################################################
      &NONBONDED14
        &LENNARD-JONES
          ATOMS       HAL2 HAL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 HAL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 HAL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL2 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL2 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL3 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
      &END NONBONDED14
#####################################################
      &NONBONDED
        &LENNARD-JONES
          ATOMS       HAL2 HAL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 HAL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL2 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 HAL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       HAL3 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL2 CTL2
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL2 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
        &LENNARD-JONES
          ATOMS       CTL3 CTL3
          EPSILON        0.0
          SIGMA          1.0
          RCUT           9.0
        &END LENNARD-JONES
      &END NONBONDED
#####################################################
    &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
      CHARGE_B
      COORD_FILE_NAME ../sample_pdb/butane.pdb
      COORDINATE pdb
    &END TOPOLOGY
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT pot_input
  RUN_TYPE md
&END GLOBAL
&MOTION
  &MD
    ENSEMBLE NVE
    STEPS 1
    TIMESTEP 0.5
    TEMPERATURE 298
  &END MD
&END MOTION
