&FORCE_EVAL
  METHOD FIST
  &EXTERNAL_POTENTIAL
    FUNCTION (X-0.1)^2+(Y+0.1)^2
  &END
  &MM
    &FORCEFIELD
      &NONBONDED
        &LENNARD-JONES
          atoms Ar Ar
          EPSILON 119.8
          SIGMA 3.405
          RCUT 8.4
        &END LENNARD-JONES
      &END NONBONDED
      &CHARGE
        ATOM Ar
        CHARGE 0.0
      &END CHARGE
    &END FORCEFIELD
    &POISSON
      &EWALD
        EWALD_TYPE none
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &CELL
      ABC 10.0 10.0 10.0
    &END CELL
    &COORD
   Ar 0.0 0.0 0.0
    &END COORD
    &TOPOLOGY
    &END TOPOLOGY
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT argon_ext
  RUN_TYPE md
&END GLOBAL
&MOTION
  &MD
    ENSEMBLE NVE
    STEPS 100
    TIMESTEP 1.
    TEMPERATURE 85.0
  &END MD
&END MOTION
