FROZEN subblock in QUILD block

Another way to introduce constraints is by freezing certain atoms. This can be achieved with the FROZEN subblock of QUILD, where either all three Cartesian (x, y, z) coordinates of an atom (or a series of atoms) can be frozen, or only one of the three:

QUILD
  FROZEN
    x      1-37   ! the X-coordinates of atoms 1 to 37 are kept frozen
    xyz   48-256  ! the X,Y,Z-coordinates of atoms 48 to 256 are kept frozen
  SUBEND
END