restraints harmonic <restraints-harmonic-statement> end

<restraints-harmonic-statement> :==

  exponent=<integer>
  --{Exponent of the harmonic energy term. Default=2}
  normal=<vector>
  --{Normal vector of a plane. To harmonically restrain the motion
     of an atom to this plane set the atom property harmonic energy
     constant to a negative value. To turn of the planar restraints
     set normal=(0,0,0).}

  --{To setup the energy constants use the do statement.}