# Re: [Wien] Band labeling

```I guess that for the "topological" characterisation you need the irreducible
representation
of the bands and not just their number```
```
e.g.: Gamma 6 (G6) means you have a e1/2 band, etc. see below

In the output of irrep you will find something like:

The point group is Td
24 symmetry operations in  5 classes
Table 81   on page  88 in Koster  et al [7]
Table 73.4 on page 637 in Altmann et al [8]

E   8C3   3C2  6IC4  6IC2`

...
--------------------------------------
G6    E1/2  2     1     0     /2    0
G7    E5/2  2     1     0    -/2    0
G8    F3/2  4    -1     0     0     0
etc

and then you find
(where 51 to 59 is the "Bandindex" of some bands at the Gamma-point (0,0,0)
that I selected to be in the vicinity of the Fermi energy, as an example)

bnd ndg  eigval     E        2IC4          C2         2C2`       2IC2"
...
...
51  2  0.505713 2.00+0.00i  1.00+0.00i  0.00+0.00i  1.41+0.00i  0.00+0.00i =G6
53  2  0.540351 2.00+0.00i  1.00+0.00i  0.00+0.00i -1.41+0.00i  0.00+0.00i =G7
55  4  0.594669 4.00+0.00i -1.00+0.00i  0.00+0.00i  0.00+0.00i  0.00+0.00i =G8
59  2  0.651442 2.00+0.00i  1.00+0.00i  0.00+0.00i -1.41+0.00i  0.00+0.00i =G7
...

I guess the Band index -- here 51 etc. -- has not much meaning other than it is
the number of a band with 1 being the number of the lowest state wherever
Wien2k starts to count in the energy window,
if you start at the bottom of the valence band you will have different numbers.
as I told before you have to run lapw1, irrep etc. for 1 k-point with the
correct switches !

Be sure to read and understand the textbooks [7,8] that are cited by Wien2k and
that are given above.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: wien-boun...@zeus.theochem.tuwien.ac.at
[wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von Gavin Abo
[gs...@crimson.ua.edu]
Gesendet: Montag, 26. Oktober 2015 10:24
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] Band labeling

Take the TiC calculation for example (TiC.tar.gz).  In TiC.tar.gz, there is the
file "TiC.spaghetti_ene".  In that file, you should see the lines:

bandindex:           5
...
0.00000   0.00000   0.00000   1.20853 -12.45555
...
bandindex:           6
...
0.00000   0.00000   0.00000   1.20853   0.66740
...
bandindex:           7
...
0.00000   0.00000   0.00000   1.20853   0.66740
...

where Gamma is (0, 0, 0) [
http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-kv-list?gnum=225&what=optimized
]

[cid:part1.06040700.06010608@crimson.ua.edu]
```
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```