XCrySDen --
(X-Window) CRYstalline Structures and DENsities

[Figure]
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Graphical selection of k-path

The k-path for band structure spaghetti plot can be selected graphically via the Tools-->k-path Selection . The following window will appear:
k-path-selection
In the above window we see two tabs entitled (i) Primitive Brillouin Zone 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
  • fcc
  • bcc
  • 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.

Specify Spaghetti Parameters - figure
In the above window we see several entries:
  • M multiplier was set to: [ ] some programs, such as for example 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 segments.
  • 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 filename extension. In particular, the following extensions are recognized:
*.kpf
the XCrySDen's k-path file. The information of the selected k-points will be saved in kind of general-information format (see an example).
*.pwscf
the format suitable for the PWscf program.
*.d3
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.


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This document was last modified on Wed Oct 7 16:08:46 CEST 2015