Dear all,
I want to calculate the band diagram of perovskite, for example: tetragonal crystal structure with some organic molecule on the edges or in center.
To do that I need to choose k-point path. It's quite difficult to choose them wisely for casual crystal cases, without molecules inside. What with the crystal cells containing molecules. If I obtain the the way of making Wigner-Seitz cell ( pl.wikipedia.org/wiki/Kom%C3%B3rka_Wignera-Seitza#/media/File:Bcc-animated.gif ) I can see that the edges of this cell in reciprocal space set the Brillouin zone (I think it's a definition), everything is okay with that for me untill I add a molecules on the unit cell edges or in the center. I belive it's gonna change the shape of the Wigner-Seitz cell of the same e.g. tetragonal structure without molecules.
Is it approximation when people in papers said that their perovskite is e.g. tetragonal and they set k-point path through the high symmetry lines and points like for simple tetragonal phase ( like for example here: en.wikipedia.org/wiki/Brillouin_zone#/media/File:Simple_Orthorhombic_Lattice_(Brillouin_zone).png )? If it is approximation what is the cost, limits etc.
X Ray diffraction of tetragonal perovskite can be used full in extracting the K values before and after adding molecules
Dear Milosz,
The first thing to do, is to check whether the crystal structure you obtain by adding your organic molecules has a Bravais lattice belonging to the tetragonal crystal system. For that, you have to remember that the Bravais lattice is defined as the periodic array in which the repeated units of the crystal are arranged. Once you have found the Bravais lattice corresponding to your structure, you can construct the reciprocal lattice vectors and then the first Brillouin zone, following the scheme you mention in your question. I hope that helps.
Dear Miłosz Martynow,
For a specific space group you can use the Bilbao Crystallographic Server, here is an example for space group 25:
http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-kv-list?gnum=45&fig=fmm2ibgc&what=data
On the other hand, if you have the coordinates of the primitive cell of your system (lattice parameters, Wyckoff positions, space group, and information from the crystallographic charts, or using a program to build the crystal structure), you can build a file in the xsf format and use the XCrysDen program to visualize the Brillouin zone and choose the k-points to create a specific path.
If you need some help just ask.
Best regards
- Badges
- Science topic
- Similar topics
- Chemistry, Organic
- Organic