Ordering of orbital angular momentum in "fat-bands" (BAND_S01_A0001.OUT)

[Christoph Wolf]

Dear all,

what is the ordering of the l (angular momentum) in the fat-bands file? I calculated silver (Ag) which has a species file configuration of (4s2 4p6 4d6 5s1)

4 0 1 2.00000 F
4 1 1 2.00000 F
4 1 2 4.00000 F
4 2 2 4.00000 F
4 2 3 6.00000 F
5 0 1 1.000000 F

and the out file of task 21 has 4 columns after column 3 (the sum of all weights)

 0.000000000      -3.379972945        0.999766    0.999766    0.000000    0.000000    0.000000

0.1258572960E-01 -3.379972650 0.999766 0.999766 0.000000 0.000000 0.000000
0.2517145920E-01 -3.379972353 0.999768 0.999767 0.000000 0.000000 0.000000
0.3775718880E-01 -3.379969926 0.999768 0.999768 0.000000 0.000000 0.000000

Does this follow the orbital ordering in the species file or is it in order of increasing l, e.g. 4s 5s 4p 4d ?

Thanks for your help in advance!

Chris

[Lars Nordström]

Dear Chris,

First I suggest you read the manual "elk.pdf" enclosed in the release. There is always some good information. For instance if you search for "band" you get 15 hits including the relevant text:
Produces a band structure along the path in reciprocal space which connects the vertices in the array vvlp1d. The band structure is obtained from the second-variational eigenvalues and is written to the file BAND.OUT with the Fermi energy set to zero. If required, band structures are plotted to files BAND Sss Aaaaa.OUT for atom aaaa of species ss, which include the band characters for each l component of that atom in columns 4 onwards. Column 3 contains the sum over l of the characters. Vertex location lines are written to BANDLINES.OUT.

So the answer to your question; in order of increasing l.

However, you have to be aware that you have semi-core states, so depending on the energy range
the s-character arise either from 4s and 5s. In your case at the low energy, –3.38 Ha, the band is purely (99.98%) 4s-character as the 5s character starts to contribute first in the valence region, starting just below Fermi energy (maybe –0.5 Ha).

Good luck,
Lars

[Christoph Wolf]

Dear Lars,

many thanks for the additional information (and for remindinding me kindly to RTFM ;)! I will give the manual a more closer look before posting here next time!

regarding the principal quantum number n I assume the distinction is up to the user based on "physical intuition" and task=21 does not allow to further separate the weights into (n,l) groups?

Best,
Chris