Option plot

This option allows you to prepare the data needed for contour plots of orbital amplitudes or total electron densities. We do not recommend to prepare plotting data this way; an easier method--with an easier syntax--is to generate these data directly by the programs, where densities (also MP2 or excited ones) and Molecular orbitals are calculated. This is described in Chapter 13. If you nevertheless want to prepare the input for plotting data as needed by moloch using define, on activating plot you get the following menu:

there are     1 data groups $grid
manipulate data group(s) $grid
 a             - add another data group
 m <integer>   - modify <integer>th data group
 m all         - modify all data groups
 d <integer>   - delete <integer>th data group
 d all         - delete all data groups
 off <integer> - switch off <integer>th data group
 off all       - switch off all data groups
 on <integer>  - switch on <integer>th data group
 on all        - switch on all data groups
 s             - scan through data groups
 *             - quit

The commands in this menu serve for the manipulation of data groups $grid in an analogous way as described for $points in the potential section above. $grid data groups contain the input information necessary to create the plot data by moloch (one data group for each plot). If you want to add a new data group you will enter this submenu:

specify the input orbital / input density :
mo <label>    - use occupied molecular orbital <label>
mo density    - use one electron density built from the
                occupied molecular orbitals
lmo <i>       - use localized molecular orbital no. <lmo>
mao <i> <k>   - use modified atomic orbital no. <i>
                centered on atom no. <k>
help          - explanation of the syntax for <label>
*             - quit

Here you may specify the orbital to be plotted. To plot the amplitude of the fifth orbital in irrep a1, e.g., you would enter mo 5a1. Equivalently you can use localized orbitals from a Boys localization procedure or modified atomic orbitals as obtained in a Roby-Davidson-Ahlrichs-Heinzmann population analysis. In the latter cases you will not have to enter an irrep label, as these orbitals are necessarily in C₁ symmetry. Instead you will have to enter the index of the orbital to be plotted (and for option mao the index of the atom at which it is situated). In all cases you will additionally have to specify the plane in which the amplitudes or densities will be monitored. To do this, you have to declare two vectors which span that plane and the origin of this new coordinate system relative to the one in which the atomic coordinates are given. Furthermore, you will have to create a grid of points on this plane. The orbital amplitude or electron density will then be calculated for every point in this grid. The grid is created by telling define the range to be included along both vectors spanning the plane (where the unit in each direction is the length of the corresponding basis vector) and the number of points to be calculated in this range. It is advantageous to use a wide grid while you test the ranges or planes which give the best results and then to switch to a finer grid for the final calculation. Finally input (MO vector) and output (plot data) files can be specified.

In case you do not want to add a new data group as described above but to change an existing one, you will be asked which one of the specifications you want to modify.