$GRID group     (not required)
 
    This group is used to input a grid (plane/2D or cube/3D)
on which properties will be calculated.  This group should be
given if WHERE=GRID in $ELPOT or $ELDENS.  This output will
be in the PUNCH file whenever OUTPUT=PUNCH or BOTH.
 
MODGRD    = 0 orthonormalize the grid vectors
          = 1 normalize the grid vectors
              (maybe useful for non-orthogonal cube files)
          (default: 0)
ORIGIN(i) = coordinates of one corner of the plane/cube.
XVEC(i)   = vector from ORIGIN to an adjacent corner "X" of
            the plane (or cube).  The XVEC direction need
            not be parallel to the X-axis of the molecule.
YVEC(i)   = vector to the adjacent corner "Y" of plane/cube.
ZVEC(i)   = vector to the adjacent corner "Z" of the cube,
            if omitted, grid (2D) is used, if given, cube (3D).
            For cube, MODGRD=0 constructs the ZVEC direction as
            XVEC x YVEC; if you use anything more complex than
            preorthogonalized vectors in cube, use MODGRD=1.
SIZE      = grid increment in all directions (default 0.25)
GRDPAD    = grid padding for cube, like GRDPAD in $FMOPRP, but
            applied to non-FMO runs (for FMO, use $FMOPRP).
            If GRDPAD is nonzero, ORIGIN/XVEC/YVEC/ZVEC are
            not needed; else they should be given (ZVEC is
            optional).
            Default: 0.
UNITS     = units used for all values in this group,
            UNITS can be either ANGS (the default) or BOHR.
 
Two dimensional grids may be drawn with the graphics
program MEPMAP provided with GAMESS.  Many GUI programs will
accept the 3-dimensional CUBE format.
 
Note that MacMolPlt draws 2D and 3D density maps without
any need to pre-compute them inside GAMESS by this group.