The k-path for band structure spaghetti plot
selected graphically via the Tools-->k-path Selection
following window will appear:
In the above window we see two tabs entitled (i) Primitive
and (ii) Conventional Brillouin zone
The latter is provided only for informational purpose, namely, to
see the shape of the BZ tessellated according to the conventional
set of reciprocal vectors. Hence for real applications we stick to
Primitive Brillouin Zone
and select a k-path by
mouse-clicking a special k-points. The BZ can be rotated by
holding-down left mouse button and dragging the mouse.
For a few Bravais lattice types, several
common k-points will be labelled automatically (thanks to Peter
Blaha), such as GAMMA, X, W, K, L points for the fcc lattice. The
automatic k-point labbeling currently supports the following
Bravais lattice types:
- primitive cubic
- primitive tetragonal
- body centered tetragonal
- primitive orthorhomobic
When we are done with the k-points selection the [OK]
button should be pressed and a new window will appear.
In the above window we see several entries:
- M multiplier was set to: [ ] some programs, such as for
CRYSTAL requires the coordinates of k-points
to be specified as "integers fractions" (for example, 1/4, 2/4,
3/4, ...). In this case the "M" would be 4. The "M" is computed
automatically by XCrySDen (only checks if the M, and
(M*kx,M*ky,M*kz) are OK).
- Total number of k-points along the path: [ ] here enter
the approximate number of f-points along the whole selected k-path.
The precise number of k-points is determined by XCrySDen in such a way that the
density of k-points is as uniform as possible for all k-line
- First/last band to conider: [ ] the integer index of the
first and the last band to consider in the spaghetti plot. Used
only when saving the k-path file in the format for
CRYSTAL; ignored otherwise. Specify two aribtrary
integers in the last case.
After pressing the [OK]
button the file-browser will appear.
The format of the saved k-path file is determined by the
In particular, the following extensions are
's k-path file. The
information of the selected k-points will be saved in kind of
general-information format (see an example
the format suitable for the PWscf
the format suitable for the
CRYSTAL property input file.
NOTE for WIEN2K users: to save the k-path in the format
suitable for WIEN2K use either the File-->Open WIEN2k ..-->Select
k-path menu or the following command-line option:
xcrysden --wien_kpath struct_file.