Keyword BOX

This keyword defines a box around a molecule for plotting (4.10.3), critical point search (4.10.4), and iso- and geosurface generation (4.10.5 and 4.10.6).
Options:
STANDARD / SMALL / LARGE

	STANDARD		A box enclosing all defined atoms with an extension of twice their covalent radii. This is the default.
	SMALL		A box enclosing all defined atoms with an extension of 1.2 times their covalent radii.
	LARGE		A box enclosing all defined atoms with an extension of four times their covalent radii. This is the default for the critical point search.

MEDIUM / COARSE / FINE

	MEDIUM		The mesh spacing of the box is 0.3 Bohr. In the case of the critical point search it is 0.5 Bohr. This is the default.
	COARSE		The mesh spacing of the box is 0.9 Bohr. In the case of the critical point search it is 1.0 Bohr.
	FINE		The mesh spacing of the box is 0.1 Bohr.
	READ		The box definition is read from the keyword body.

Description:
The box size is specified with the options STANDARD, SMALL, and LARGE. The box is always created in STANDARD ORIENTATION (see 4.1.6) and, therefore, is symmetry-adapted to the molecule. The options MEDIUM, COARSE, and FINE define the mesh spacing within the box. The FINE mesh spacing will generate huge data files and thus is appropriate only for small systems. Via the READ option, the box can be explicitly defined in the keyword body of BOX. If only a part of the molecule should be considered, the box can be defined simply by the atoms that should be included. In this case, the STANDARD, SMALL, and LARGE, as well as the MEDIUM, COARSE, and FINE options remain active. For a SMALL box with FINE resolution containing the H1 and O atoms of the water molecule, the input has the form:

 
 BOX SMALL FINE READ
 O H1

Note that all atoms are defined in one input line. Instead of the explicit definition of each atom, elements can be used for the box definition, too. Therefore, a SMALL box with MEDIUM resolution containing only the hydrogen atoms of water can be defined as:

 
 BOX SMALL MEDIUM READ
 H

Alternatively, the plot box can be defined by vectors in the keyword body of BOX. In this case the options STANDARD, SMALL, and LARGE, as well as MEDIUM, COARSE, and FINE lose their meanings. The following format is used for the box definition via vectors:

The $\vec{r}_0 = (x_0, y_0, z_0)$ position vector defines the origin of the box. The other three vectors $\vec{r}_i = (x_i, y_i, z_i)$, $\vec{r}_j = (x_j, y_j, z_j)$ and $\vec{r}_k = (x_k, y_k, z_k)$ span the box as sketched above. NI, NJ and NK specify the number of points along the directions $\vec{r}_i - \vec{r}_0$, $\vec{r}_j - \vec{r}_0$ and $\vec{r}_k - \vec{r}_0$, respectively. Please note that these three vectors, $\vec{r}_i - \vec{r}_0$, $\vec{r}_j - \vec{r}_0$ and $\vec{r}_k - \vec{r}_0$, must be perpendicular to each other. In the case of a plane (two-dimensional box), definitions of NK, XK, YK, and ZK are not needed. For a line (one-dimensional box), only NI, $\vec{r}_0$, and $\vec{r}_i$ must be defined. The explicit definition of a two-dimensional plot box is given in the following example:

 PLOT LAPLACIAN
 VXCTYP AUXIS VWN
 #
 GEOMETRY ANGSTROM
 N 0.0 0.0 0.0
 N 0.0 0.0 1.114553
 #
 BOX
 200  200
 0.0 -2.0 -2.0
 0.0  2.0 -2.0
 0.0 -2.0  3.114553

The definition of a one-dimensional plot box is described in Example on page of the deMon2k Tutorial.