General remarks

Options 4, 5 and (in the case of a spin-polarised calculation) 55 work similarly. The difference is only in physical meaning of the objects lev00 is dealing with:

• 4 - partial electron density, Eq. (3.2), works only with CASTEP; in fact, it is redundant for VASP and SIESTA as option 5 (next) completely replaces it
• 5 - total (all occupied bands) or partial electron density or any other file (e.g. an electrostatic potential) of the same format
• 55 - total spin density; equivalent to 5, but reads in specifically the spin density (which is usually contained at the end of the full density file, at least, in the cases of VASP and SIESTA).

In fact, in all these cases the structure of the files is the same or similar (for the given DFT code). Moreover, files of identical structure (if named appropriately) can also be read in and analysed, see Sections 4 and 5. For convenience, in the forthcoming Sections we shall be talking about density.

We shall first consider option 5 in detail. After that, percularities of options 4 (Section 3.6.3.15) and 55 (Section 3.6.3.14) will also be mentioned.

When activating option 5, the file name to be read in is implicit for SIESTA, CASTEP and CETEP: job name appended by .RHO, fort.16 and fort.200, respectively. In the case of VASP, three possibilities exist: CHGCAR (total density), PARCHG (partial density), LOCPOT (electrostatic potential). The formats of these three files are similar. Then the file is read in:

Reading in charge density, please wait ...

it is done 10 %

it is done 20 %

it is done 30 %

it is done 40 %

it is done 50 %

it is done 60 %

it is done 70 %

it is done 80 %

it is done 90 %

it is done 100 %

Done!

The charge is = 0.800338E+01

.....> Total charge = 8.00337610269848 <.....

Done!

It shows the total number of electrons in the system^3.5 (8 in the example above). Then, the main menu of this option is opened up:

...... Choose between line or plane ......

NUMBER OF THE CURRENT PLOT: 1

1. Plot density along a line

2. Plot density in a plane

3. Amount of charge inside a sphere

4. Exploration of the density

5. Dipole moment

6. Quadrupole moment

7. Get density via point charges: match moments & potential

8. Cutting atoms out of the density

9. Write non-zero density as CHGCAR.new

10. Write density in gOpenMol cube format

11. Get density via point charges: match density

12. Transform the charge density for a shifted system

12. Return to the previous menu

The options of this menu are explained in some detail in the Sections below. At this point, note the plot number in the first line. This is automatically updated every time you return to this menu. This number is used in file names created in various options and is necessary to avoid creating files with identical names.